Chapter V: Front Matter (5)

The most able exponent of this subject in Great Britain was John
Curtis, whose treatise on _Farm Insects_, published in 1860, is still
the standard British work dealing with the insect foes of corn, roots,
grass and stored corn. The most important works dealing with fruit and
other pests come from the pens of Saunders, Lintner, Riley,
Slingerland and others in America and Canada, from Taschenberg, Lampa,
Reuter and Kollar in Europe, and from French, Froggatt and Tryon in
Australia. It was not until the last quarter of the 19th century that
any real advance was made in the study of economic entomology. Among
the early writings, besides the book of Curtis, there may also be
mentioned a still useful little publication by Pohl and Kollar,
entitled _Insects Injurious to Gardeners, Foresters and Farmers_,
published in 1837, and Taschenberg's _Praktische Insecktenkunde_.
American literature began as far back as 1788, when a report on the
Hessian fly was issued by Sir Joseph Banks; in 1817 Say began his
writings; while in 1856 Asa Fitch started his report on the "Noxious
Insects of New York." Since that date the literature has largely
increased. Among the most important reports, &c., may be mentioned
those of C.V. Riley, published by the U.S. Department of Agriculture,
extending from 1878 to his death, in which is embodied an enormous
amount of valuable matter. At his death the work fell to Professor
L.O. Howard, who constantly issues brochures of equal value in the
form of Bulletins of the U.S. Department of Agriculture. The chief
writings of J.A. Lintner extend from 1882 to 1898, in yearly parts,
under the title of _Reports on the Injurious Insects of the State of
New York_. Another author whose writings rank high on this subject is
M.V. Slingerland, whose investigations are published by Cornell
University. Among other Americans who have largely increased the
literature and knowledge must be mentioned F.M. Webster and E.P. Felt.
In 1883 appeared a work on fruit pests by William Saunders, which
mainly applies to the American continent; and another small book on
the same subject was published in 1898 by Miss Ormerod, dealing with
the British pests. In Australia Tryon published a work on the _Insect
and Fungus Enemies of Queensland_ in 1889. Many other papers and
reports are being issued from Australia, notably by Froggatt in New
South Wales. At the Cape excellent works and papers are prepared and
issued by the government entomologist, Dr Lounsbury, under the
auspices of the Agricultural Department; while from India we have
Cotes's _Notes on Economic Entomology_, published by the Indian Museum
in 1888, and other works, especially on tea pests.

Injurious insects occur among the following orders: _Coleoptera_, _Hymenoptera_, _Lepidoptera_, _Diptera_, _Hemiptera_ (both _heteroptera_ and _homoptera_), _Orthoptera_, _Neuroptera_ and _Thysanoptera_. The order _Aptera_ also contains a few injurious species.

Among the _Coleoptera_ or beetles there is a group of world-wide pests, the _Elateridae_ or click beetles, the adults of the various "wireworms." The insects in the larval or wireworm stage attack the roots of plants, eating them away below the ground. The eggs deposited by the beetle in the ground develop into yellowish-brown wire-like grubs with six legs on the first three segments and a ventral prominence on the anal segment. The life of these subterranean pests differs in the various species; some undoubtedly (_Agriotes lineatum_) live for three or four years, during the greater part of which time they gnaw away at the roots of plants, carrying wholesale destruction before them. When mature they pass deep into the ground and pupate, appearing after a few months as the click beetles (fig. 1). Most crops are attacked by them, but they are particularly destructive to wheat and other cereals. With such subterranean pests little can be done beyond rolling the land to keep it firm, and thus preventing them from moving rapidly from plant to plant. A few crops, such as mustard, seem deleterious to them. By growing mustard and ploughing it in green the ground is made obnoxious to the wireworms, and may even be cleared of them. For root-feeders, bisulphide of carbon injected into the soil is of particular value. One ounce injected about 2 ft. from an apple tree on two sides has been found to destroy all the ground form of the woolly aphis. In garden cultivation it is most useful for wireworm, used at the rate of 1 ounce to every 4 sq. yds. It kills all root pests.

In Great Britain the flea beetles (_Halticidae_) are one of the most serious enemies; one of these, the turnip flea (_Phyllotreta nemorum_), has in some years, notably 1881, caused more than L500,000 loss in England and Scotland alone by eating the young seedling turnips, cabbage and other _Cruciferae_. In some years three or four sowings have to be made before a "plant" is produced, enormous loss in labour and cost of seed alone being thus involved. These beetles, characterized by their skipping movements and enlarged hind femora, also attack the hop (_Haltica concinna_), the vine in America (_Graptodera chalybea_, Illig.), and numerous other species of plants, being specially harmful to seedlings and young growth. Soaking the seed in strong-smelling substances, such as paraffin and turpentine, has been found efficacious, and in some districts paraffin sprayed over the seedlings has been practised with decided success. This oil generally acts as an excellent preventive of this and other insect attacks.

In all climates fruit and forest trees suffer from weevils or _Curculionidae_. The plum curculio (_Conotrachelus nenuphar_, Herbst) in America causes endless harm in plum orchards; curculios in Australia ravage the vines and fruit trees (_Orthorrhinus klugii_, Schon, and _Leptops hopei_, Bohm, &c.). In Europe a number of "long-snouted" beetles, such as the raspberry weevils (_Otiorhynchus picipes_), the apple blossom weevil (_Anthonomus pomorum_), attack fruit; others, as the "corn weevils" (_Calandra oryzae_ and _C. granaria_), attack stored rice and corn; while others produce swollen patches on roots (_Ceutorhynchus sulcicollis_), &c. All these _Curculionidae_ are very timid creatures, falling to the ground at the least shock. This habit can be used as a means of killing them, by placing boards or sacks covered with tar below the trees, which are then gently shaken. As many of these beetles are nocturnal, this trapping should take place at night. Larval "weevils" mostly feed on the roots of plants, but some, such as the nut weevil (_Balaninus nucum_), live as larvae inside fruit. Seeds of various plants are also attacked by weevils of the family _Bruchidae_, especially beans and peas. These seed-feeders may be killed in the seeds by subjecting them to the fumes of bisulphide of carbon. The corn weevils (_Calandra granaria_ and _C. oryzae_) are now found all over the world, in many cases rendering whole cargoes of corn useless.

The most important Hymenopterous pests are the sawflies or _Tenthredinidae_, which in their larval stage attack almost all vegetation. The larvae of these are usually spoken of as "false caterpillars," on account of their resemblance to the larvae of a moth. They are most ravenous feeders, stripping bushes and trees completely of their foliage, and even fruit. Sawfly larvae can at once be recognized by the curious positions they assume, and by the number of pro-legs, which exceeds ten. The female lays her eggs in a slit made by means of her "saw-like" ovipositor in the leaf or fruit of a tree. The pupae in most of these pests are found in an earthen cocoon beneath the ground, or in some cases above ground (_Lophyrus pini_). One species, the slugworm (_Eriocampa limacina_), is common to Europe and America; the larva is a curious slug-like creature, found on the upper surface of the leaves of the pear and cherry, which secretes a slimy coating from its skin. Currant and gooseberry are also attacked by sawfly larvae (_Nematus ribesii_ and _N. ventricosus_) both in Europe and America. Other species attack the stalks of grasses and corn (_Cephus pygmaeus_). Forest trees also suffer from their ravages, especially the conifers (_Lophyrus pini_). Another group of Hymenoptera occasionally causes much harm in fir plantations, namely, the _Siricidae_ or wood-wasps, whose larvae burrow into the trunks of the trees and thus kill them. For all exposed sawfly larvae hellebore washes are most fatal, but they must not be used over ripe or ripening fruit, as the hellebore is poisonous.

The order Diptera contains a host of serious pests. These two-winged insects attack all kinds of plants, and also animals in their larval stage. Many of the adults are bloodsuckers (_Tabanidae_, _Culicidae_, &c.); others are parasitic in their larval stage (_Oestridae_, &c.). The best-known dipterous pests are the Hessian fly (_Cecidomyia destructor_), the pear midge (_Diplosis pyrivora_), the fruit flies (_Tephritis Tyroni_ of Queensland and _Halterophora capitata_ or the Mediterranean fruit fly), the onion fly (_Phorbia cepetorum_), and numerous corn pests, such as the gout fly (_Chloropstaeniopus_) and the frit fly (_Oscinis frit_). Animals suffer from the ravages of bot flies (_Oestridae_) and gad flies (_Tabanidae_); while the tsetse disease is due to the tsetse fly (_Glossina morsitans_), carrying the protozoa that cause the disease from one horse to another. Other flies act as disease-carriers, including the mosquitoes (_Anopheles_), which not only carry malarial germs, but also form a secondary host for these parasites. Hundreds of acres of wheat are lost annually in America by the ravages of the Hessian fly; the fruit flies of Australia and South Africa cause much loss to orange and citron growers, often making it necessary to cover the trees in muslin tents for protection. Of animal pests the ox warbles (_Hypoderma lineata_ and _H. bovis_) are the most important (see fig. 2). The "bots" or larvae of these flies live under the skin of cattle, producing large swollen lumps--"warbles"--in which the "bots" mature (fig. 2). These parasites damage the hide, set up inflammation, and cause immense loss to farmers, herdsmen and butchers. The universal attack that has been made upon this pest has, however, largely decreased its numbers. In America cattle suffer much from the horn fly (_Haematobia serrata_). The dipterous garden pests, such as the onion fly, carrot fly and celery fly, can best be kept in check by the use of paraffin emulsions and the treatment of the soil with gas-lime after the crop is lifted. Cereal pests can only be treated by general cleanliness and good farming, and of course they are largely kept down by the rotation of crops.

Lepidopterous enemies are numerous all over the world. Fruit suffers much from the larvae of the _Geometridae_, the so-called "looper-larvae" or "canker-worms." Of these geometers the winter moth (_Cheimatobia brumata_) is one of the chief culprits in Europe (fig. 3). The females in this moth and in others allied to it are wingless. These insects pass the pupal stage in the ground, and reach the boughs to lay their eggs by crawling up the trunks of the trees. To check them, "grease-banding" round the trees has been adopted; but as many other pests eat the leafage, it is best to kill all at once by spraying with arsenical poisons. Among other notable Lepidopterous pests are the "surface larvae" or cutworms (_Agrotis spp._), the caterpillars of various Noctuae; the codling moth (_Carpocapsa pomonella_), which causes the maggot in apples, has now become a universal pest, having spread from Europe to America and to most of the British Colonies. In many years quite half the apple crop is lost in England owing to the larvae destroying the fruit. Sugar-canes suffer from the sugar-cane borer (_Diatioca sacchari_) in the West Indies; tobacco from the larvae of hawk moths (_Sphingidae_) in America; corn and grass from various Lepidopterous pests all over the world. Nor are stored goods exempt, for much loss annually takes place in corn and flour from the presence of the larvae of the Mediterranean flour moth (_Ephestia kuniella_); while furs and clothes are often ruined by the clothes moth (_Tinea trapezella_).

By far the most destructive insects in warm climates belong to the Hemiptera, especially to the _Coccidae_ or scale insects. All fruit and forest trees suffer from these curious insects, which in the female sex always remain apterous and apodal and live attached to the bark, leaf and fruit, hidden beneath variously formed scale-like coverings. The male scales differ in form from the female; the adult male is winged, and is rarely seen. The female lays her eggs beneath the scaly covering, from which hatch out little active six-legged larvae, which wander about and soon begin to form a new scale. The _Coccidae_ can, and mainly do, breed asexually (parthenogenetically). One of the most important is the San Jose scale (_Aspidiotus perniciosus_), which in warm climates attacks all fruit and many other trees, which, if unmolested, it will soon kill (fig. 4). These scales breed very rapidly; Howard states one may give rise to a progeny of 3,216,080,400 in one year. Other scale insects of note are the cosmopolitan mussel scale (_Mytilaspis pomorum_) and the Australian _Icerya purchasi_. The former attacks apple and pear; the latter, which selects orange and citron, was introduced into America from Australia, and carried ruin before it in some orange districts until its natural enemy, the lady-bird beetle, _Vedalia cardinalis_, was also imported.

After the _Coccidae_ the next most important insects economically are the plant lice or _Aphididae_. These breed with great rapidity under favourable conditions: one by the end of the year will be accountable, according to Linnaeus, for the enormous number of a quintillion of its species. Aphides are born, as a rule, alive, and the young soon commence to reproduce again. Their food consists mainly of the sap obtained from the leaves and blossom of plants, but some also live on the roots of plants (_Phylloxera vastatrix_ and _Schizoneura lanigera_). Aphides often ruin whole crops of fruit, corn, hops, &c., by sucking out the sap, and not only check growth, but may even entail the death of the plant. Reproduction is mainly asexual, the females producing living young without the agency of a male. Males in nearly all species appear once a year, when the last female generation, the ovigerous generation, is fertilized, and a few large ova are produced to carry on the continuity of the species over the winter. Some aphides live only on one species of plant, others on two or more plants. An example of the latter is seen in the hop aphis (_Phorodon humuli_), which passes the winter and lives on the sloe and damson in the egg stage until the middle of May or later, and then flies off to the hops, where it causes endless harm all the summer (fig. 5); it flies back to the prunes to lay its eggs when the hops are ripe. Another aphis of importance is the woolly aphis (_Schizoneura lanigera_) of the apple and pear: it secretes tufts of white flocculent wool often to be seen hanging in patches from old apple trees, where the insects live in the rough bark and form cankered growths both above and below ground. Aphides are provided with a mealy skin, which does not allow water to be attached to it, and thus insecticides for destroying them contain soft soap, which fixes the solution to the skin; paraffin is added to corrode the skin, and the soft soap blocks up the breathing pores and so produces asphyxiation.

Amongst _Orthoptera_ we find many noxious insects, notably the locusts, which travel in vast cloud-like armies, clearing the whole country before them of all vegetable life. The most destructive locust is the migratory locust (_Locusta migratoria_), which causes wholesale destruction in the East. Large pits are dug across the line of advance of these great insect armies to stop them when in the larval or wingless stage, and even huge bonfires are lighted to check their flight when adult. So dense are these "locust clouds" that they sometimes quite darken the air. The commonest and most widely distributed migratory locust is _Pachytylus cinerascens_. The mole cricket (_Gryllotalpa vulgaris_) and various cockroaches (_Blattidae_) are also amongst the pests found in this order.

Of _Neuroptera_ there are but few injurious species, and many, such as the lace wing flies (_Hemerobiidae_), are beneficial.

_The Treatment of Insect Pests._--One of the most important ways of keeping insect pests in check is by "spraying" or "washing." This method has made great advances in recent years. All the pioneer work has been done in America; in fact, until the South-Eastern Agricultural College undertook the elucidation of this subject, little was known of it in England except by a few growers. The results and history of this essential method of treatment are embodied in Professor Lodemann's work on the _Spraying of Plants_, 1896. In this treatment we have to bear in mind what the entomologist teaches us, that is, the nature, habits and structure of the pest.

For insects provided with a biting mouth, which take nourishment from
the whole leaf, shoot or fruit, the poisonous washes used are chiefly
arsenical. The two most useful arsenical sprays are Paris green and
arsenate of lead. To make the former, mix 1 oz. of the Paris green
with 15 gallons of soft water, and add 2 oz. of lime and a small
quantity of agricultural treacle; the latter is prepared by dissolving
3 oz. of acetate of lead in a little water, then 1 oz. of arsenate of
soda in water and mixing the two well together, and adding the whole
to 16 gallons of soft water; to this is added a small quantity of
coarse treacle. For piercing-mouthed pests like _Aphides_ no wash is
of use unless it contains a basis of soft soap. This soft-soap wash
kills by contact, and may be prepared in the following way:--Dissolve
6 to 8 lb. of the best soft soap in boiling soft water and while still
hot (but of course taken off the fire) add 1 gallon of paraffin oil
and churn well together with a force-pump; the whole may then be mixed
with 100 gallons of soft water. The oil readily separates from the
water, and thus a perfect emulsion is not obtained: this difficulty
has been solved by Mr Cousin's paraffin naphthalene wash, which is
patented, but can be made for private use. It is prepared as
follows:--Soft soap, 6 lb. dissolved in 1 quart of water; naphthalene,
10 oz. mixed with 1-1/2 pint of paraffin; the whole is mixed together.
When required for use, 1 lb. of the compound is dissolved in 5 to 10
gallons of warm water.

These two washes are essential to the well-being of every orchard in
all climates. Not only can we now destroy larval and adult insects,
but we can also attack them in the egg stage by the use of a caustic
alkali wash during the winter; besides destroying the eggs of such
pests as the _Psyllidae_, red spider, and some aphides, this also
removes the vegetal encumbrances which shelter numerous other insect
pests during the cold part of the year. Caustic alkali wash is
prepared by dissolving 1 lb. of crude potash and 1 lb. of caustic soda
in soft water, mixing the two solutions together, adding to them 3/4
lb. of soft soap, and diluting with 10 gallons of soft water when
required for use. Another approved insecticide for scale insects is
resin wash, which acts in two ways: first, corroding the soft scales,
and second, fixing the harder scales to stop the egress of the hexapod
larvae. It is prepared as follows:--First crush 8 lb. of resin in a
sack, and then place the resin in warm water and boil in a cauldron
until thoroughly dissolved; then melt 10 lb. of caustic soda in enough
warm water to keep it liquid, and mix with the dissolved resin; keep
stirring until the mixture assumes a clear coffee-colour, and for ten
minutes afterwards; then add enough warm water to bring the whole up
to 25 gallons, and well stir. Bottle this off, and when required for
use dilute with three times its bulk of warm soft water, and spray
over the trees in the early spring just before the buds burst. For
mites (_Acari_) sulphur is the essential ingredient of a spray. Liver
of sulphur has been found to be the best form, especially when mixed
with a paraffin emulsion. Bud mites (_Phytoptidae_, fig. 6) are of
course not affected. Sulphur wash is made by adding to every 10
gallons of warm paraffin emulsion or paraffin-naphthalene-emulsion 7
oz. of liver of sulphur, and stirring until the sulphur is well mixed.
This is applied as an ordinary spray. Nursery stock should always be
treated, to kill scale, aphis and other pests which it may carry, by
the gas treatment, particularly in the case of stock imported from a
foreign climate. This treatment, both out of doors and under glass, is
carried out as follows:--Cover the plants in bulk with a light
gas-tight cloth, or put them in a special fumigating house, and then
place 1 oz. of cyanide of potassium in lumps in a dish with water
beneath the covering, and then pour 1 oz. of sulphuric acid over it
(being careful not to inhale the poisonous fumes) for every 1000 cub.
ft. of space beneath the cover. The gas generated, prussic acid,
should be left to work for at least an hour before the stock is
removed, when all forms of animal life will be destroyed.

For spraying, proper instruments must be used, by means of which the
liquid is sent out over the plants in as fine a mist as possible.
Numerous pumps and nozzles are now made by which this end is attained.
Both horse and hand machines are employed, the former for hops and
large orchards, the latter for bush fruit and gardens. In America,
where trees in parks as well as orchards and gardens are treated,
steam-power is sometimes used. Among the most important sprayers are
the Strawson horse sprayers and the smaller Eclair and Notus knapsack
pumps, carried on the back (fig. 7). The nozzles for "mistifying" the
wash most in use are known as the Vermorel and Riley's, which can be
fitted to any length of tubing, so as to reach any height, and can be
turned in any direction. The pumps in the machine keep the insecticide
constantly mixed, and at the same time force the wash with great
strength through the nozzle, and so to the exterior, as a fine mist;
every part of the plant is thus affected.

_Beneficial Insects_ have also to be considered in economic entomology. They are of two kinds--(1) those that help to keep down an excess of other insects by acting either as parasites or by being insectivorous in habit; and (2) insects of economic value, such as the bee and silkworm. Amongst the most important friends to the farmer and gardener are the Hymenopterous families of ichneumon flies (_Ichneumonidae_ and _Braconidae_); the Dipterous families _Syrphidae_ and _Tachinidae_; the Coleopterous families _Coccinellidae_ and _Carabidae_; and the Neuropterous _Hemerobiidae_, or lace-wing flies. Ichneumon flies lay their eggs either in the larvae or ova of other insects, and the parasites destroy their host. In this way the Hessian fly is doubtless kept in check in Europe, and the aphides meet with serious hindrance to their increase. If a number of plant-lice are examined, a few will be found looking like little pearls; these are the dried skins of those that have been killed by _Ichneumonidae_. The _Syrphidae_, or hover flies, are almost exclusively aphis-feeders in their larval stage. _Tachina_ flies attack lepidopterous larvae. One of the most notable examples of the use of insect allies is the case of the Australian lady-bird, _Vedalia cardinalis_, which, in common with all lady-birds, feeds off _Aphidae_ and _Coccidae_. The Icerya scale (_Icerya purchasi_) imported into America ruined the orange groves, but its enemy, the _Vedalia_, was also imported from Australia, and counteracted its abnormal increase with such great results that the crippled orange groves are now once more profitable. (F. V. T.)

ECONOMICS (from the Gr. [Greek: oikonomike], sc. [Greek: techne], from [Greek: oikos], a house, and [Greek: nomos], rule,--the "art of household management"), the general term, with its synonym "political economy," for the science or study of wealth (welfare) and its production, applicable either to the individual, the family, the State, or in the widest sense, the world. How far the same considerations apply to all these spheres is one of the problems of economic thought in its widest sense. The term "economy" (q.v.) by itself, which should strictly mean the art of applying money (or wealth) wisely, has commonly come to mean the art of saving money, or spending as little as possible. In practice the study of "political" economy is mainly devoted to the sphere of the State; the welfare of the individual as a member of the State, and of the State in its relation to the world, being internal aspects of the prosperity of the State itself. Economics thus includes the discussion of all the numerous factors which make life profitable, whether to the nation or to the business, or to the individual man. It may be conceived either as an historical science (What principles have in fact paid?), or as an abstract science (What are the true principles which must pay, presupposing an ideal?). Economists at different times have studied both aspects, according to their lights, and influenced by historical conditions of philosophic thought. A text-book on economics necessarily deals, therefore, with the whole subject in a manner which need not here be followed, since separate articles are devoted in this work to the biographies of writers on economics, and also to the principal economic questions involved, under their own headings. In this article we propose therefore to confine ourselves to discussing the character and subject-matter of the science, indicating its relation to other sciences, and explaining the methods by which economists reach their conclusions.

We understand by economics the science which investigates the manner in which nations or other larger or smaller communities, and their individual members, obtain food, clothing, shelter and whatever else is considered desirable or necessary for the maintenance and improvement of the conditions of life. It is thus the study of the life of communities with special reference to one side of their activity. It necessarily involves the scientific examination of the structure and organization of the community or communities in question; their history, their customs, laws and institutions; and the relations between their members, in so far as they affect or are affected by this department of their activity.

At the root of all economic investigation lies the conception of the standard of life of the community. By this expression we do not mean an ideal mode of living, but the habits and requirements of life generally current in a community or grade of society at a given period. The standard of life of the ordinary well-to-do middle class in England, for example, includes not only food, clothing and shelter of a kind different in many respects from that of a similar class in other countries and of other classes in England, but a highly complicated mechanism, both public and private, for ministering to these primary needs, habits of social intercourse, educational and sanitary organization, recreative arrangements and many other elements. Many influences operating for a long period of time on the character and the environment of a class go to determine its standard of life. In a modern industrial community it is possible to express this standard fairly accurately for the purposes of economic investigation in terms of money (q.v.). But it is doubtful whether the most complete investigation would ever enable us to include all the elements of the standard of life in a money estimate. The character, tastes and capacity for management of different individuals and groups differ so widely that equal incomes do not necessarily imply identity of standard. In the investigation of past times, the incommensurate elements of well-being are so numerous that merely money estimates are frequently misleading. The conception of the standard of life involves also some estimate of the efforts and sacrifices people are prepared to make to obtain it; of their ideals and character; of the relative strength of the different motives which usually determine their conduct. But no carefully devised calculus can take the place of insight, observation and experience. The economist should be a man of wide sympathies and practical sagacity, in close touch with men of different grades, and, if possible, experienced in affairs.

Character of subject-matter.

It is evident that no permanent classification is possible of what is or is not of economic significance. No general rules, applicable to all times, can be laid down as to what phenomena must be examined or what may be neglected in economic inquiry. The different departments of human activity are organically connected, and all facts relating to the life of a community have a near or remote economic significance. For short historical periods, indeed, many phenomena are so remotely connected with the ordinary business of life that we may ignore them. But at any moment special causes may bring into the field of economic inquiry whole departments of life which have hitherto been legitimately ignored. In times past, biblical exegesis, religious ideals, and ecclesiastical organization, the purely political aims of statesmen, chance combinations of party politics and the intrigues of diplomatists, class prejudice, social conventions, apparently sudden changes of economic policy, capricious changes of fashion--all these causes and many others have exerted a direct and immediate influence on the economic life of the community. In our own day we have had many illustrations of the manner in which special circumstances may at once bring an almost unnoticed series of scientific investigations into direct and vital relation with the business world. The economist must, therefore, not only be prepared to take account of the physical features of the world, the general structure and organization of the industry and commerce of different states, the character of their administration and other important causes of economic change. He must be in touch with the actual life of the community he is studying, and cultivate "that openness and alertness of the mind, that sensitiveness of the judgment, which can rapidly grasp the significance of at first sight unrelated discoveries or events."

Some people are of opinion that the factors to be taken account of in economic investigation are so numerous that progress on these lines is impossible. It would certainly be impossible if we had to begin _de novo_ to construct the whole fabric of economic science. But, as we shall see, it is no more necessary to do this in the world of science than it is in the world of business or politics. There is in existence a vast store of accumulated knowledge, and few, if any, departments of economics have been left quite unilluminated by the researches of former generations. Progress is the result of adaptation rather than reconstruction. It must be remembered also that economic work in modern times is carried on by consciously or unconsciously associated effort, and although it must always require high qualities of judgment, capacity and energy, many of the difficulties which at first sight appear so insuperable give way when they are attacked. In some ways also the study of highly developed organizations like the modern industrial state is simpler than that of earlier forms of society.

Ancient and modern conditions in England.

In the earliest times for which we have abundant material the economic life of England had already reached in certain directions a high degree of complexity. Even in the rural districts, manorial records reveal the existence of a great variety of classes and groups of persons engaged in the performance of economic functions. The lord of the manor with his officials and retainers, the peasantry bound to him by ties of personal dependence and mutual rights and obligations, constituted a little world, in which we can watch the play of motives and passions not so dissimilar as we are sometimes led to believe from those of the great modern world. In many a country district the gradations of social rank were more continuous, the opportunities of intercourse more frequent, and the capacity for organization greater than in modern times. The manorial accounts were kept with precision and detail, and we are told that a skilled official could estimate to the utmost farthing the value of the services due from the villein to his lord. The manor was indeed self-sufficient and independent in the sense that it could furnish everything required by the majority of the inhabitants, and that over the greater part of rural England production was not carried on with a view to a distant market. But in the earliest times the manor was subjected to external influences of great importance. Vast areas of the country were in fact under the single control of a territorial lord or an ecclesiastical foundation. Every manor composing these great fiefs was likely to be affected by the policy or the character of the administration of the feudal lord, and he, again, by the policy or the difficulties, the strength or the weakness, of the central government. Foreign trade and foreign intercourse were undeveloped, but their influence was in historical times never entirely absent, while the influence of Roman law and the Christian Church constantly tended to modify the manorial organization. In the towns the division of labour had proceeded much further than in the rural districts, and there were in existence organized bodies, such as the Gild Merchant and the crafts, whose functions were primarily economic. But one of the most striking characteristics of town life in the middle ages was the manner in which municipal and industrial privileges and responsibilities were interwoven. In modern times the artisan, however well trained, efficient and painstaking he may be, does not, in virtue of these qualities, enjoy any municipal or political privileges. By means of his trade union, co-operative society or club he may gain some experience in the management of men and business, and in so far as the want of a sufficient income does not constitute an insuperable difficulty, he may share in the public life of the country. But in his character as artisan he enjoys no municipal or political privileges. In the middle ages this differentiation of the industrial, municipal and political life had not taken place, and in order to understand the working of at first sight purely economic regulations it is necessary to make a close study of the functions of local government. But this, after all, does not carry us very far. From the very nature of the records in which we study the town life of the middle ages, it follows that we obtain from them only a one-sided view. No one knows what proportion of the industrial population was included in the organized gilds, or how complete was the control exercised by these bodies over their members. Elaborate regulations were in force, but no one knows how elastic they were in practice. Medieval Englishmen were particularly apt to put their aspirations into a legal form, and then rest satisfied with their achievement. The number of regulations is scarcely to be regarded as a test of their administrative success. Further, as the country became more consolidated and the central government extended its authority over economic affairs, new regulations came into force, new organs of government appeared, which were sometimes in conflict, sometimes in harmony, with the existing system, and it becomes for a time far more difficult to obtain a clear view of the actual working of economic institutions. Thus the study of the economic life of the middle ages is one of the most complicated subjects which can engage the attention of man. It is impossible to carry the process of isolation very far. The different threads of social activity are so closely interwoven that we cannot follow any one for very long without forming wrong impressions, and it becomes necessary to turn back and study others which seemed at first sight unrelated to the subject of our investigations. Under an apparently uniform and stable system of social regulation there was much variation and movement, the significance of which it is impossible to estimate. Materials for forming such an estimate no doubt exist, but before doing so we have to study in infinite detail a vast number of separate manors, municipalities or other separate economic areas. This involves great industry on the part of many scientific workers. Meanwhile we can _illustrate_ the economic life of the middle ages, describe its main features, indicate the more important measures of public policy and draw attention to some of the main lines of development.

Conditions of economic science.

It is only as we approach more modern times that the conditions of economic study are realized and economic science, as we understand it, becomes possible. Those conditions are: (i.) the life of the state or other community or communities we are studying must be so differentiated that we can isolate those functions which are wholly or predominantly economic. The "separation of employments" is not only a condition of economic efficiency; it was necessary before we could have an economic science. (ii.) We must be in a position so far to understand and estimate the character and motives of different classes and groups in these communities that we can rightly interpret their action. This condition cannot be realized without great difficulty, for "economic motives" are very different in different periods, nations and classes, and even for short periods of time in the same country are modified by the influence of other motives of an entirely different order. In studying the economic history of the 18th century, for example, it is not enough to assume with Defoe that "gain is the design of merchandise." We have to be saturated, as it were, with 18th-century influences, so that we can realize the conditions in which industry and trade were carried on, before we can rightly explain the course of development. In our own day labour disputes, to take another example, can scarcely ever be resolved into a question of merely pecuniary gain or loss. The significance of the amount of money involved varies greatly for different trades, and can only be understood by reference to the character and habits of the people concerned. But questions of sentiment, shop-feeling and trade customs invariably play an important part. (iii.) Economics can never lead to anything but hypothetical results unless we not only realize that we must "take account of" other than the purely economic factors, but also give due weight and significance to these factors. No explanation of the industrial situation in Germany, for example, would be intelligible or satisfactory even from the economic point of view which ignored the significance of the political conditions which Germans have to deal with. So, again, it is impossible to make a useful comparative estimate of the advantages and disadvantages of the transport systems of England, the United States and Germany, unless we keep constantly in view the very different geographical, military and political conditions which these systems have to satisfy. (iv.) Sufficient information must be available to enable us to test the validity of our hypotheses and conclusions. Whatever "method" of economic investigation we employ, we must at every stage see how far our reasoning is borne out by the actual experience of life. This obvious condition of scientific inquiry is very far from being completely realized even at the present time. It implies the existence of a well-trained class engaged in the work of collecting information, and much organization both by the state and private bodies. These four conditions can be reduced to two. The community we are studying must have reached such a stage of development that its economic functions and those immediately cognate to them form a well-defined group, and adequate means must be available so that we can, as it were, watch the performance of these functions and test our hypotheses and conclusions by observation and experience.

It is easy to understand, therefore, why we trace the beginnings of economics, so far as England is concerned, in the 16th century, and why the application of strict scientific tests in this subject of human study has become possible only in comparatively recent times. Medieval economics was little more than a casuistical system of elaborate and somewhat artificial rules of conduct. From the close of the middle ages until the middle of the 18th century thousands of pamphlets and other works on economic questions were published, but the vast majority of the writers have little or no scientific importance. Their works frequently contain information given nowhere else, and throw much light on the state of opinion in the age in which they wrote. It is also possible to find in them many anticipations of the views of the economists of later times; but such statements were as a rule generated merely by the heat of controversy on some measure or event of practical importance, and when the controversy died down were seldom regarded or incorporated in a scientific system. Trade bias, personal impressions and guesswork took the place of scientific method. This was inevitable in the absence of trustworthy information on an adequate scale, and from the immediately practical aims of the writers. But from the end of the 17th century economics has been definitely recognized as a subject of scientific study.

Necessity of economic science.

In modern times the conditions which have made economic science possible have also made it necessary. While it is impossible to give a strictly economic interpretation of the earlier history of nations, economic interests so govern the life and determine the policy of modern states that other forces, like those of religion and politics, seem to play only a subsidiary part, modifying here and there the view which is taken of particular questions, but not changing in any important degree the general course of their development. This may be, in the historical sense, merely a passing phase of human progress, due to the rapid extension of the industrial revolution to all the civilized and many of the uncivilized nations of the world, bringing in its train the consolidation of large areas, a similarity of conditions within them, and amongst peoples and governments a great increase in the strength of economic motives. When the world has settled down to the new conditions, if it ever does so, we may be confronted with problems similar to those which our forefathers had to solve. But, for the time, if we know the economic interests of nations, classes and individuals, we can tell with more accuracy than ever before how in the long run they will act. Public policy therefore requires the closest possible study of the economic forces which are moulding the destinies of the great nations of the world. In most civilized countries except England this is recognized, and adequate provision is made for the study of economic science. But the subject is not only of immediate concern to the state in its corporate and public capacity. The neglect of it in the domain of private business can now only lead to disastrous results. To quote from a useful work (_National Education: a Symposium_, 1901), "the commercial supremacy of England was due to a variety of causes, of which superior intelligence, in the ordinary business sense, was not the most important. Her insular position, continuity of political development and freedom from domestic broils played an important part in bringing about a steady and continuous growth of industry and manufactures for several generations before the modern era. The great wars of the 18th and the beginning of the 19th century, which arrested the growth of continental nations, gave England the control of the markets of the world. When peace was restored, England enjoyed something in the nature of a monopoly. The competition of France ceased for a time to be an important factor. What is now the German empire was a mere congeries of small states, waging perpetual tariff wars upon each other. In the old Prussian provinces alone there were fifty-three different customs frontiers, and German manufactures could not develop until the growth of the Zollverein brought with it commercial consolidation, internal freedom and greater homogeneity of economic conditions. The industries of the United States were in their infancy. Thus the productive power of England was unrivalled, and her manufactures and business men, under a regime rapidly approximating to complete freedom of trade, could reap the full advantages to be derived from the possession of great national resources and production by machinery. Commercial supremacy required not so much highly trained intelligence amongst manufacturers and merchants as keen business instinct and a certain rude energy. In the last generation all that has changed, and the change is of a permanent character. The struggle of the future must inevitably be between a number of great nations, more or less equally well equipped, carrying on production by the same general methods, each one trying to strengthen its industrial and commercial position by the adoption of the most highly developed machinery, and all the methods suggested by scientific research, policy or experience. Under these conditions, it is no longer possible for the individual merchant, or for small groups of merchants, to acquaint themselves, by personal experience alone, with more than a fractional part of the causes which affect the business in which they are engaged. The spread of the modern industrial system has brought with it the modern state, with its millions of consumers, its vast area, its innumerable activities, its complicated code of industrial and commercial law. At the same time, the revolution in the means of transport and communication has destroyed, or is tending to destroy, local markets, and closely interwoven all the business of the world. Events in the most distant countries, industrial and commercial movements at first sight unrelated to the concerns of the individual merchant, now exert a direct and immediate influence upon his interests. The technical training of the factory or the office, the experience of business, the discharge of practical duties, necessary as they are, do not infallibly open the mind to the large issues of the modern business world, and can never confer the detailed acquaintance with facts and principles which lie outside the daily routine of the individual, but are none the less of vital importance." Economics, therefore, under modern conditions, is not only a subject which may usefully occupy the attention of a leisured class of scientific men. It should form part of the training of educated men of all classes, on grounds of public policy and administrative and business efficiency.

Relations between economics and other sciences.

The relations between economics and other sciences cannot be stated in a very general form. They vary for different periods, and are not the same for all branches of economics. There is no subject of human study which may not be at some time or other of economic significance, and anything which affects the character, the ideals or the environment of man may make it necessary to modify our assumptions and our reasoning with regard to his conduct in economic affairs. But if the economist, while studying one side of man's activities, must also cultivate all other branches of human learning, it is obvious that no substantial progress can be made. The economist frankly assumes the reality of the existing world and takes men as they are, or as they have been if he is studying past times. His assumptions are based upon ordinary observation and experience, and are usually accurate in proportion to his practical shrewdness and sagacity, so that he is not interested in the speculative flights of philosophy, except in so far as they influence or have influenced conduct. In times past, and to a less extent in our own day, philosophical conceptions have formed the basis of great systems of politics and economics. The historical relations between philosophy and economics are of great importance in tracing the development of the latter, and have done much to determine its present form. But the modern conception of society or the state owes more to biology than philosophy, and actual research has destroyed more frequently than it has justified the assumptions of the older philosophical school. Experimental psychology may in course of time have an important bearing on economics, but the older science cannot be said to be of much significance except in its historical aspects. Ethics is in much the same position. That is, it is possible to conceive of an ethical science which would extend considerably our knowledge of economic affairs, but no important new principle or original discovery, relevant to economic investigation, has come from that quarter in recent years, and at present ethics has more to learn from economics than the latter has from ethics. It is in the adaptation of biological conceptions and methods, in the positive contributions of jurisprudence, law and history, in the rigorous application, where possible, of quantitative tests, that the explanation of the present position of economics is to be found. Mathematics has influenced the form and the terminology of the science, and has sometimes been useful in analysis; but mathematical methods of reasoning, in their application to economics, while possessing a certain fascination, are of very doubtful utility.

Method of economic investigation.

There is no method of investigation which is peculiarly economic or of which economics has the monopoly. In every age economists have applied the methods ordinarily in use amongst scientific men. There would probably have been no controversy at all on this subject but for the fact that economics was elaborated into systematic form, and made the basis of practical measures of the greatest importance, long before the remarkable development in the 19th century of historical research, experimental science and biology. The application of the _a priori_ method in economics was an accident, due to its association with other subjects and the general backwardness of other sciences rather than any exceptional and peculiar character in the subject-matter of the science itself. The methods applied to economics in the 18th and the early part of the 19th century were no more invented with a special view to that subject than the principles of early railway legislation, in the domain of practical policy, were devised with a special view to what was then a new means of transport. As a matter of fact, discussions of method and the criticism of hypotheses and assumptions are very rarely found in early economic works. It is only by reference to the prevailing ideas in philosophy and politics that we can discover what was in the minds of their authors. The growth of a science is much like the growth of a constitution. It proceeds by adaptation and precedent. The scientific and historical movement of the 19th century was revolutionary in character. When it began to affect economics, many people were afraid that the whole fabric of science would be destroyed and the practical gains it had achieved, jeopardized. These fears were justified, in so far as those who entertained them shut their eyes to everything new and assumed an attitude of no compromise. Where the newer methods were assimilated, the position of economics was strengthened and its practical utility increased. General discussion of method, however, is rarely profitable. In all branches of economics, even in what is called the pure theory, there is an implied reference to certain historical or existing conditions of a more or less definite character; to the established order of an organized state or other community, at a stage of development which in its main features can be recognized. In all economic investigation assumptions must be made, but we must see that they are legitimate in view of the actual life and character of the community or communities which are the subject of investigation. In common with other sciences, economics makes use of "abstractions"; but if for some problems we employ symbolic processes of reasoning, we must keep clearly in view the limits of their significance, and neither endow the symbols with attributes they can never possess, nor lose sight of the realities behind them. Every hypothesis must be tested by an appeal to the facts of life, and modified or abandoned if it will not bear examination, unless we are convinced on genuine evidence that it may for a time be employed as a useful approximation, without prejudice to the later stages of the investigation we are conducting.

An illustration of economic method.