Chapter XII: Abraham Ibn Daud (1)

What was poison to Judah Halevi is meat to Abraham Ibn Daud. We must, he says, investigate the principles of the Jewish religion and seek to harmonize them with true philosophy. And in order to do these things properly a preliminary study of science is necessary. Nowadays all this is neglected and the result is confusion in fundamental principles, for a superficial and literal reading of the Bible leads to contradictory views, not to speak of anthropomorphic conceptions of God which cannot be the truth. Many of our day think that the study of philosophy is injurious. This is because it frequently happens in our time that a person who takes up the study of philosophy neglects religion. In ancient times also this happened in the person of Elisha ben Abuya, known by the name of Aher. Nevertheless science was diligently studied in Rabbinic times. Witness what was said concerning Rabbi Yohanan ben Zakkai, Samuel and the Synhedrin.[221] It cannot be that God meant us to abstain from philosophical study, for many statements in the Bible, such as those relating to freedom of the will, to the nature of God and the divine attributes, to the creation of the world, and so on, are a direct stimulus to such investigation. Surely mental confusion cannot be the purpose God had in mind for us. If he preferred our ignorance he would not have called our attention to these matters at all.[222]

This, as we see, is decidedly a different point of view from that of Judah Halevi. The difference between them is not due to a difference in their age and environment, but solely to personal taste and temperament. Toledo was the birthplace of Ibn Daud as it was of Halevi. And the period in which they lived was practically the same. Judah Halevi's birth took place in the last quarter of the eleventh century, whereas Ibn Daud is supposed to have been born about 1110, a difference of some twenty-five or thirty years. The philosopher whom Judah Halevi presents to us as the typical representative of his time is an Aristotelian of the type of Alfarabi and Avicenna. And it is the same type of philosophy that we meet in the pages of the "Emunah Ramah" (Exalted Faith), Ibn Daud's philosophical work.[223] Whereas, however, Judah Halevi was a poet by the grace of God, glowing with love for his people, their religion, their language and their historic land, Ibn Daud leaves upon us the impression of a precise thinker, cold and analytical. He exhibits no graces of style, eloquence of diction or depths of enthusiasm and emotion. He passes systematically from one point to the next, uses few words and technical, and moves wholly in the Peripatetic philosophy of the day. In 1161, the same year in which the Emunah Ramah was composed, he also wrote a historical work, "Sefer Hakabala" (Book of Tradition), which we have; and in 1180, regarded by some as the year of his death, he published an astronomical work, which is lost. This gives an index of his interests which were scientific and philosophic. Mysticism, whether of the poetic or the philosophic kind, was far from his nature; and this too may account for the intense opposition he shows to Solomon Ibn Gabirol. On more than one occasion he gives vent to his impatience with that poetic philosopher, and he blames him principally for two faults. Choosing to devote a whole book to one purely metaphysical topic, in itself not related to Judaism, Gabirol, we are told by Ibn Daud, gave expression to doctrines extremely dangerous to the Jewish religion. And apart from his heterodoxy, he is philosophically incompetent and his method is abominable. His style is profuse to the point of weariness, and his logic carries no conviction.[224]

While Abraham Ibn Daud is thus expressly unsympathetic to Gabirol and tacitly in disagreement with Halevi (he does not mention him), he shows the closest relation to Maimonides, whose forerunner he is. We feel tempted to say that if not for Ibn Daud there would have been no Maimonides. And yet the irony of history has willed that the fame of being the greatest Jewish philosopher shall be Maimonides's own, while his nearest predecessor, to whose influence he owed most, should be all but completely forgotten. The Arabic original of Ibn Daud's treatise is lost, and the Hebrew translations (there are two) lay buried in manuscript in the European libraries until one of them was published by Simson Weil in 1852.[225]

Abraham Ibn Daud is the first Jewish philosopher who shows an intimate knowledge of the works of Aristotle and makes a deliberate effort to harmonize the Aristotelian system with Judaism. To be sure, he too owes his Aristotelian knowledge to the Arabian exponents of the Stagirite, Alfarabi and Avicenna, rather than to the works of Aristotle himself. But this peculiarity was rooted in the intellectual conditions of his time, and must not be charged to his personal neglect of the sources. And Maimonides does nothing more than repeat the effort of Ibn Daud in a more brilliant and masterly fashion.

The development of the three religious philosophies in the middle ages, Jewish, Christian and Mohammedan, followed a similar line of progression. In all of them it was not so much a development from within, the unfolding of what was implicit and potential in the original germ of the three respective religions, as a stimulus from without, which then combined, as an integral factor, with the original mass, and the final outcome was a resultant of the two originally disparate elements. We know by this time what these two elements were in each case, Hellenic speculation, and Semitic religion in the shape of sacred and revealed documents. The second factor was in every case complete when the process of fusion began. Not so the first. What I mean is that not all of the writings of Greek antiquity were known to Jew, Christian and Mohammedan at the beginning of their philosophizing career. And the progress in their philosophical development kept equal step with the successive accretion of Greek philosophical literature, in particular Aristotle's physical, psychological and metaphysical treatises, and their gradual purgation of Neo-Platonic adhesions.

The Syrian Christians, who were the first to adopt Greek teachings, seem never to have gone beyond the mathematical and medical works of the Greeks and the logic of Aristotle. The Arabs began where their Syrian teachers ended, and went beyond them. The Mutakallimun were indebted to the Stoics,[226] the Pure Brethren to the Neo-Platonists; and it was only gradually that Aristotle became the sole master not merely in logic, which he always had been, but also in physics, metaphysics and psychology. Alfarabi, Avicenna and Averroes represent so many steps in the Aristotelization of Arabic philosophy.

Christian mediæval thought, which was really a continuation of the Patristic period, likewise began with Eriugena in the ninth century under Platonic and Neo-Platonic influences. Of Aristotle the logic alone was known, and that too only in small part. Here also progress was due to the increase of Aristotelian knowledge; though in this case it was not gradual as with the Arabs before them, but sudden. In the latter part of the twelfth and the early part of the thirteenth century, through the Crusades, through the Moorish civilization in Spain, through the Saracens in Sicily, through the Jews as translators and mediators, Aristotle invaded Christian Europe and transformed Christian philosophy. Albertus Magnus, Thomas Aquinas, Duns Scotus, William of Occam are the results of this transformation.

The same thing holds true of the Jews. Their philosophizing career stands chronologically between that of their Arab teachers and their Christian disciples. And the line of their development was similar. It was parallel to that of the Arabs. First came Kalam in Saadia, Mukammas, the Karaites Al Basir and Jeshua ben Judah. Then Neo-Platonism and Kalam combined, or pure Neo-Platonism, in Bahya, Gabirol, Ibn Zaddik and the two Ibn Ezras, Abraham and Moses. In Judah Halevi, so far as philosophy is represented, we have Neo-Platonism and Aristotelianism. Finally in Ibn Daud and Maimonides, Neo-Platonism is reduced to the vanishing point, and Aristotelianism is in full view and in possession of the field. After Maimonides the only philosopher who deviates from the prescribed path and endeavors to uproot Aristotelian authority in Judaism is Crescas. All the rest stand by Aristotle and his major domo, Maimonides.

This may seem like a purely formal and external mode of characterizing the development of philosophical thought. But the character of mediæval philosophy is responsible for this. Their ideal of truth as well as goodness was in the past. Knowledge was thought to have been discovered or revealed in the past,[227] and the task of the philosopher was to acquire what was already there and to harmonize contradictory authorities. Thus the more of the past literature that came to them, the greater the transformation in their own philosophy.

The above digression will make clear to us the position of Ibn Daud and his relation to Maimonides. Ibn Daud began what Maimonides finished--the last stage in the Aristotelization of Jewish thought. Why is it then that so little was known about him, and that his important treatise was neglected and practically forgotten? The answer is to be found partly in the nature of the work itself and partly in historical circumstances.

The greatest and most abiding interest in intellectual Jewry was after all the Bible and the Talmud. This interest never flagged through adversity or through success. The devotion paid to these Jewish classics and sacred books may have been fruitful in original research and intelligent application at one time and place and relatively barren at another. Great men devoted to their study abounded in one country and were relatively few in another. The nature of the study applied to these books was affected variously by historical conditions, political and economic; and the cultivation or neglect of the sciences and philosophy was reflected in the style of Biblical and Talmudical interpretation. But at all times and in all countries, under conditions of comparative freedom as well as in the midst of persecution, the sacred heritage of Israel was studied and its precepts observed and practiced. In this field alone fame was sure and permanent. All other study was honored according to the greater or less proximity to this paramount interest. In times of freedom and of great philosophic and scientific interest like that of the golden era in Spain, philosophical studies almost acquired independent value. But this independence, never quite absolute, waned and waxed with external conditions, and at last disappeared entirely. If Ibn Daud had made himself famous by a Biblical commentary or a halakic work, or if his philosophic treatise had the distinction of being written in popular and attractive style, like Bahya's "Duties of the Hearts," or Halevi's "Cusari," it might have fared better. As it is, it suffers from its conciseness and technical terminology. Add to this that it was superseded by the "Guide of the Perplexed" of Maimonides, published not many years after the "Emunah Ramah," and the neglect of the latter is completely explained.

Abraham ibn Daud tells us in the introduction to his book that it was written in response to the question of a friend concerning the problem of free will. The dilemma is this. If human action is determined by God, why does he punish, why does he admonish, and why does he send prophets? If man is free, then there is something in the world over which God has no control. The problem is made more difficult by the fact that Biblical statements are inconsistent, and passages may be cited in favor of either of the theories in question. This inconsistency is to be explained, however, by the circumstance that not all Biblical phrases are to be taken literally--their very contradiction is a proof of this. Now the passages which require exegetic manipulation are in general those which seem opposed to reason. Many statements in the Bible are in fact intended for the common people, and are expressed with a view to their comprehension, and without reference to philosophic truth. In the present instance the objections to determinism are much greater and more serious than those to freedom. In order to realize this, however, it is necessary to investigate the principles of the Jewish religion and seek to harmonize them with true philosophy. This in turn cannot be done without a preliminary study of science. A question like that of determinism and freedom cannot be decided without a knowledge of the divine attributes and the consequences flowing from them. But to understand these we must have a knowledge of the principles of physics and metaphysics.[228] Accordingly Abraham Ibn Daud devotes the entire first part of the "Emunah Ramah" to general physics and metaphysics in the Aristotelian conception of these terms.

Concerning the kind of persons for whom he wrote his book, he says, I advise everyone who is perfectly innocent, who is not interested in philosophical and ethical questions like that of determinism and freedom on the ground that man cannot grasp them; and is entirely unconcerned about his ignorance--I advise such a person to refrain from opening this book or any other of a similar nature. His ignorance is his bliss, for after all the purpose of philosophy is conduct. On the other hand, those who are learned in the principles of religion and are also familiar with philosophy need not my book, for they know more than I can teach them here. It is the beginner in speculation who can benefit from this work, the man who has not yet been able to see the rational necessity of beliefs and practices which he knows from tradition.

That the principles of the Jewish religion are based upon philosophic foundations is shown in Deuteronomy 4, 6: "Keep therefore and do them; for this is your wisdom and your understanding in the sight of the peoples, which shall hear all these statutes, and say, surely this great nation is a wise and understanding people." This cannot refer to the ceremonial precepts, the so-called "traditional" commandments; for there is nothing in them to excite the admiration of a non-Jew. Nor can it refer to the political and moral regulations, for one need not profess the Jewish or any other religion in order to practice them; they are a matter of reason pure and simple. The verse quoted can only mean that the other nations will be seized with admiration and wonder when they find that the fundamental principles of the Jewish religion, which we received by tradition and without effort, are identical with those philosophical principles at which they arrived after a great deal of labor extending over thousands of years.[229]

Ibn Daud is not consistent in his idea of the highest aim of man. We have just heard him say that the purpose of philosophy is conduct. This is true to the spirit of Judaism which, despite all the efforts of the Jewish philosophers to the contrary, is not a speculative theology but a practical religion, in which works stand above faith. But as an Aristotelian, Ibn Daud could not consistently stand by the above standpoint as the last word in this question. Accordingly we find him elsewhere in true Aristotelian fashion give priority to theoretical knowledge.

Judging from the position of man among the other creatures of the sublunar world, we come to the conclusion, he tells us, that that which distinguishes him above his surroundings, namely, his rational soul, is the aim of all the rest; and they are means and preparations for it. The rational soul has two forms of activity. It may face upward and receive wisdom from the angels (theoretical knowledge). Or it may direct its attention downwards and judge the other corporeal powers (practical reason). But it must not devote itself unduly or without system to any one occupation. The aim of man is wisdom, science. Of the sciences the highest and the aim of all the rest is the knowledge of God. The body of man is his animal, which leads him to God. Some spend all their time in feeding the animal, some in clothing it, and some in curing it of its ills. The latter is not a bad occupation, as it saves the body from disease and death, and so helps it to attain the higher life. But to think of the study of medicine as the aim of life and devote all one's time to it is doing injury to one's soul. Some spend their time in matters even less significant than this, _viz._, in studying grammar and language; others again in mathematics and in solving curious problems which are never likely to happen. The only valuable part here is that which has relation to astronomy. Some are exclusively occupied in "twisting threads." This is an expression used by an Arabian philosopher,[230] who compares man's condition in the world to that of a slave who was promised freedom and royalty besides if he made the pilgrimage to Mecca and celebrated there. If he made the journey and was prevented from reaching the holy city, he would get freedom only; but if he did not undertake the trip he would get nothing. The three steps in the realization of the purpose are thus: making the preparations for the journey, getting on the road and passing from station to station, and finally wandering about in the place of destination. One small element in the preparation for the journey is twisting the threads for the water bottle. Medicine and law as means of gaining a livelihood and a reputation represent the stage of preparing for the journey. They are both intended to improve the ills of life, whether in the relations of man to man as in law; or in the treatment of the internal humors as in medicine. Medicine seems more important, for on the assumption of mankind being just, there would be no need of law, whereas the need for medicine would remain. To spend one's whole life in legal casuistry and the working out of hypothetical cases on the pretext of sharpening one's wits, is like being engaged in twisting threads continually--a little is necessary, but a great deal is a waste of time. It would be best if the religious man would first learn how to prove the existence of God, the meaning of prophecy, the nature of reward and punishment and the future world, and how to defend these matters before an unbeliever. Then if he has time left, he may devote it to legalistic discussions, and there would be no harm.

Self-examination, in order to purify oneself from vices great and small, represents the second stage of getting on the road and travelling from station to station. The final stage, arriving in the holy city and celebrating there, is to have a perfect knowledge of God. He who attains this is the best of wise men, having the best of knowledge, which deals with the noblest subject. The reader must not expect to find it all in this book. If he reads this and does not study the subject for himself, he is like a man who spent his time in reading about medicine and cannot cure the simplest ailment. The knowledge of God is a form that is bestowed from on high upon the rational soul when she is prepared by means of moral perfection and scientific study. The prophet puts all three functions of the soul on the same level, and gives preference to knowledge of God. "Thus saith the Lord," says Jeremiah (9, 22), "Let not the wise man glory in his wisdom [rational soul], neither let the mighty man glory in his might [spirited soul], let not the rich man glory in his riches [nutritive soul]: but let him that glorieth glory in this, that he understandeth, and knoweth me...." Jeremiah also recommends (_ib._) knowing God through his deeds--"That I am the Lord which exercise loving-kindness"--in order that man may imitate him.[231]

We have now a general idea of Ibn Daud's attitude and point of view; and in passing to the details of his system it will not be necessary to rehearse all the particulars of his thought, much of it being common to all mediæval writers on Jewish philosophy. We shall confine ourselves to those matters in which Ibn Daud contributed something new, not contained in the writings of his predecessors.

Following the Aristotelian system, he begins by describing substance and accident and gives a list and characterization of the ten categories. This he follows up by showing that the classification of the ten categories lies at the basis of the 139th Psalm. It needs not our saying that it must be an extraordinary mode of exegesis that can find such things in such unusual places. But the very strangeness of the phenomenon bears witness to the remarkable influence exerted by the Aristotelian philosophy upon the thinking of the Spanish Jews at that time.[232]

From the categories he passes to a discussion of the most fundamental concepts in the Aristotelian philosophy, matter and form. And here his method of proving the existence of matter is Aristotelian and new. It is based upon the discussion in Aristotle's Physics, though not necessarily derived from there directly. Primary matter, he says, is free from all form. There must be such, for in the change of one thing to another, of water to air for example, it cannot be the _form_ of water that receives the form of air; for the form of water disappears, whereas that which receives the new form must be there. Reason therefore leads us to assume a common substrate of all things that are subject to change. This is primary matter, free from all form. This matter being at the basis of all change and becoming, could not itself have come to be through a similar process, or we should require another matter prior to it, and it would not be the prime matter we supposed it to be. This last argument led Aristotle to the concept of an eternal matter, the basis of becoming for all else besides, itself not subject to any such process. It is an ultimate, to ask for the origin of which would signify to misunderstand the meaning of origin. All things of the sublunar world originate in matter, hence matter itself is the unoriginated, the eternal.

Ibn Daud as a Jew could not accept this solution, and so he cut the knot by saying that while it is true that matter cannot originate in the way in which the composite objects of the sublunar world come to be, it does not yet follow that it is absolutely ultimate and eternal. God alone is the ultimate and eternal; nothing else is. Matter is a relative ultimate; relative, that is, to the composite and changeable objects of our world; but it is itself an effect of God as the universal cause. God created it outright.

Prime matter, therefore, represents the first stage in creation. The next stage is the endowment of this formless matter with corporeality in the abstract, _i. e._, with extension. Then come the specific forms of the four elements, then their compounds through mineral, plant and animal to man. This is not new; we have already met with it in Gabirol and Ibn Zaddik. Nor is the following significant statement altogether new, though no one before Ibn Daud expressed it so clearly and so definitely. It is that the above analysis of natural objects into matter, universal body, the elements, and so on, is not a physical division but a logical. It does not mean that there was a time when prime matter actually existed as such before it received the form of corporeality, and then there existed actually an absolute body of pure extension until it received the four elements. No, nothing has existence _in actu_ which has not individuality, including not only form, but also accidents. The above analysis is theoretical, and the order of priority is logical not real. In reality only the complete compound of matter and form (the individual) exists.

Allusion to matter and form is also found in the Bible in Jeremiah (18, 1ff.), "Arise and go down to the potter's house.... Then I went down to the potter's house, and, behold, he wrought his work on the wheels.... Behold as the clay in the potter's hand...."[233]

The next important topic analyzed by Ibn Daud is that of motion. This is of especial importance to Ibn Daud because upon it he bases a new proof of the existence of God, not heretofore found in the works of any of his predecessors. It is taken from Aristotle's Physics, probably from Avicenna's treatises on the subject, is then adopted by Maimonides, and through his example no doubt is made use of by Thomas Aquinas, the great Christian Scholastic of the thirteenth century, who gives it the most prominent place in his "Summa Contra Gentiles."

Ibn Daud does not give Aristotle's general definition of motion as the "actualization of the potential qua potential" (_cf._ above, p. xxxii), but his other remarks concerning it imply it. Motion, he says, is applied first to movement in place, and is then transferred to any change which is gradual, such as quantitative or qualitative change. Sudden change is not called motion. As the four elements have all the same matter and yet possess different motions--earth and water moving downward, fire and air upward--it cannot be the matter which is the cause of their motions. It must therefore be the forms, which are different in different things.

Nothing can move itself. While it is true that the form of a thing determines the kind of motion it shall have, it cannot in itself produce that motion, which can be caused only by an efficient cause from without. The case of animal motions may seem like a refutation of this view, but it is not really so. The soul and the body are two distinct principles in the animal; and it is the soul that moves the body. The reason why a thing cannot move itself is because the thing which is moved is potential with reference to that which the motion is intended to realize, whereas the thing causing the motion is actual with respect to the relation in question. If then a thing moved itself, it would be actual and potential at the same time and in the same relation, which is a contradiction. The Bible, too, hints at the idea that every motion must have a mover by the recurring questions concerning the origin of prophetic visions, of the existence of the earth, and so on. Such are the expressions in Job (38, 36, 37): "Who hath put wisdom in the inward parts?" "Who can number the clouds by wisdom?" In Proverbs (30, 4): "Who hath established all the ends of the earth?" and in many passages besides.[234]

The question of infinity is another topic of importance for proving the existence of God. We proceed as follows: An infinite line is an impossibility. For let the lines _a_------------_b_ be infinite in the _c_------|-----_d_ _e_ directions _b_, _d_. Take away from _cd_ a finite length = _ce_, and pull up the line _ed_ so that _e_ coincides with _c_. Now if _ed_ is equal to _ab_, and _cd_ was also equal to _ab_ by hypothesis, it follows that _ed_ = _cd_, which is impossible, for _ed_ is a part of _cd_. If it is shorter than _cd_ and yet is infinite, one infinite is shorter than another infinite, which is also impossible. The only alternative left is then that _ed_ is finite. If then we add to it the finite part _ce_, the sum, _ce_ + _ed_ = _cd_, will be finite, and _cd_ being equal to _ab_ by hypothesis, _ab_ is also finite. Hence there is no infinite line. If there is no infinite line, there is no infinite surface or infinite solid, for we could in that case draw in them infinite lines. Besides we can prove directly the impossibility of infinite surface and solid by the same methods we employed in line.

We can prove similarly that an infinite series of objects is also an impossibility. In other words, infinite number as an actuality is impossible because it is a contradiction in terms. A number of things means a known number; infinite means having no known number. A series is something that has beginning, middle and end. Infinite means being all middle. We have thus proved that an actual infinite is impossible, whether as extension or number. And the Bible also alludes to the finiteness of the universe in the words of Isaiah (40, 12): "Who hath measured the waters in the hollow of his hand...," intimating that the universe is capable of being measured.

We must prove next that no finite body can have an infinite power. For let the line _ae_ ------------- be a finite line having an infinite _a_ _b_ _c_ _d_ _e_ power. Divide into the several parts _ab_, _be_, _cd_, _de_, etc. If every one of the parts has an infinite power, _ab_ has an infinite power, _ac_ a greater infinite power, _ad_ a still greater, _ae_ a still greater, and so on. But this is absurd, for there cannot be anything greater than the infinite. It follows then that each of the parts has a finite power; and as the sum of finites is finite, the line _ae_ also has a finite power. All these principles we must keep in mind, for we shall by means of them prove later the existence and incorporeality of God.[235]

As the concepts of physics are essential for proving the existence of God, so are the principles of psychology of importance in showing that there are intermediate beings between God and the corporeal substances of the world. These are called in the Bible angels. The philosophers call them secondary causes.

Accordingly Ibn Daud follows his physical doctrines with a discussion of the soul. There is nothing new in his proof that such a thing as soul exists. It is identical with the deduction of Joseph Ibn Zaddik (_supra_, p. 134). Stone and tree and horse and man are all bodies and yet the last three have powers and functions which the stone has not, _viz._, nutrition, growth and reproduction. Horse and man have in addition to the three powers above mentioned, which they have in common with tree, the powers of sensation and motion and imagination, which plants have not. Finally man is distinguished above all the rest of animal creation in possessing the faculty of intelligence, and the knowledge of art and of ethical discrimination. All these functions cannot be body or the result of body, for in that case all corporeal objects should have all of them, as they are all bodies. We must therefore attribute them to an extra-corporeal principle; and this we call soul. As an incorporeal thing the soul cannot be strictly defined, not being composed of genus and species; but we can describe it in a roundabout way in its relation to the body. He then gives the Aristotelian definition of the soul as "the [first] entelechy of a natural body having life potentially" (_cf._ above, p. xxxv).

Like many of his predecessors who treated of the soul, Ibn Daud also finds it necessary to guard against the materialistic theory of the soul which would make it the product of the elemental mixture in the body, if not itself body. This would reduce the soul to a phenomenon of the body, or in Aristotelian terminology, an accident of the body, and would deprive it of all substantiality and independence, not to speak of immortality. How can that which is purely a resultant of a combination of elements remain when its basis is gone? Accordingly Ibn Daud takes pains to refute the most important of these phenomenalistic theories, that of Hippocrates and Galen. Their theory in brief is that the functions which we attribute to the soul are in reality the results of the various combinations of the four elementary qualities, hot, cold, moist, dry. The more harmonious and equable the proportion of their union, the higher is the function resulting therefrom. The difference between man and beast, and between animal and plant is then the difference in the proportionality of the elemental mixture. They prove this theory of theirs by the observation that as long as the mixture is perfect the activities above mentioned proceed properly; whereas as soon as there is a disturbance in the mixture, the animal becomes sick and cannot perform his activities, or dies altogether if the disturbance is very great. The idea is very plausible and a great many believe it, but it is mistaken as we shall prove.

His refutation of the "accident" or "mixture" theory of the soul, as well as the subsequent discussion of the various functions, sensuous and rational, of the tripartite soul, are based upon Ibn Sina's treatment of the same topic, and we have already reproduced some of it in our exposition of Judah Halevi. We shall therefore be brief here and refer only to such aspects as are new in Ibn Daud, or such as we found it advisable to omit in our previous expositions.

His main argument against the materialistic or mechanistic theory of the soul is that while a number of phenomena of the growing animal body can be explained by reference to the form of the mixture in the elementary qualities, not all aspects can be thus explained. Its growth and general formation may be the result of material and mechanical causes, but not so the design and purpose evident in the similarity, to the smallest detail, of the individuals of a species, even when the mixture is not identical. There is no doubt that there is wisdom here working with a purpose. This is soul. There is another argument based upon the visible results of other mixtures which exhibit properties that cannot be remotely compared with the functions we attribute to the soul. The animal and the plant exhibit activities far beyond anything present in the simple elements of the mixture. There must therefore be in animals and plants something additional to the elements of the mixture. This extra thing resides in the composite of which it forms a part, for without it the animal or plant is no longer what it is. Hence as the latter is substance, that which forms a part of it is also substance; for accident, as Aristotle says, is that which resides _in_ a thing but not as forming a part of it.

We have now shown that the soul is substance and not accident. We must still make clear in which of the four senses of the Aristotelian substance the soul is to be regarded. By the theory of exclusion Ibn Daud decides that the soul is substance in the sense in which we apply that term to "form." The form appears upon the common matter and "specifies" it, and makes it what it is, bringing it from potentiality to actuality. It is also the efficient and final cause of the body. The body exists for the sake of the soul, in order that the soul may attain its perfection through the body. As the most perfect body in the lower world is the human body, and it is for the sake of the soul, it follows that the existence of the sublunar world is for the sake of the human soul, that it may be purified and made perfect by science and moral conduct.

While we have proved that soul is not mixture nor anything like it, it is nevertheless true that the kind of soul bestowed upon a given body depends upon the state of the mixture in the elementary qualities of that body. Thus we have the three kinds of soul, vegetative, animal and human or rational. We need not follow Ibn Daud in his detailed descriptions of the functions of the several kinds of soul, as there is little that is new and that we have not already met in Joseph Ibn Zaddik and Judah Halevi. Avicenna (Ibn Sina) is the common source for Halevi and Ibn Daud, and the description of the inner senses is practically identical in the two, with the slight difference that Halevi attributes to the "common sense" the two functions which are divided in Ibn Daud between the common sense and the power of representation.

The soul is not eternal. It was created and bestowed upon body. When a body comes into being, the character of its mixture determines that a soul of a certain kind shall be connected with it. The other alternatives are (1) that the soul existed independently before the body, is then connected with the body and dies with the death of the latter; or (2) it remains after the death of the body. The first alternative is impossible; because if the soul is connected with the body in order to die with it, its union is an injury to the soul, for in its separate existence it was free from the defects of matter. The second alternative is equally impossible; for if the soul was able to exist without the body before the appearance of the latter and after its extinction, of what use is its connection with the body? Far from being of any benefit, its union with the body is harmful to the soul, for it is obliged to share in the corporeal accidents. Divine wisdom never does anything without a purpose.

The truth is that the soul does not exist before the body. It arises at the same time as, and in connection with body, realizing and actualizing the latter. Seed and sperm have in them the possibility of becoming plant and animal respectively. But they need an agent to bring to actuality what is in them potentially. This agent--an angel or a sphere, or an angel using a sphere as its instrument--bestows forms upon bodies, which take the places of the previous forms the bodies had. The sphere or star produces these forms (or souls) by means of its motions, which motions ultimately go back to the first incorporeal mover, by whose wisdom forms are connected with bodies in order to perfect the former by means of the latter.

Now the human soul has the most important power of all other animals, that of grasping intelligibles or universals. It is also able to discriminate between good and evil in conduct, moral, political and economic. The human soul, therefore, has, it seems, two powers, _theoretical_ and _practical_. With the former it understands the simple substances, known as angels in the Bible and as "secondary causes" and "separate intelligences" among the philosophers. By this means the soul rises gradually to its perfection. With the practical reason it attends to noble and worthy conduct. All the other powers of the soul must be obedient to the behests of the practical reason. This in turn is subservient to the theoretical, putting its good qualities at the disposition of the speculative reason, and thus helping it to come into closer communion with the simple substances, the angels and God. This is the highest power there is in the _world of nature_.

We must now show that the rational power in man is neither itself body nor is it a power residing in a corporeal subject. That it is not itself body is quite evident, for we have proved that the lower souls too, those of animals and plants, are not corporeal. But we must show concerning the rational power that it is independent of body in its activity. This we can prove in various ways. One is by considering the object and content of the reason. Man has general ideas or universal propositions. These are not divisible. An idea cannot be divided into two halves or into parts. Reason in action consists of ideas. Now if reason is a power residing in a corporeal subject, it would be divisible like the latter. Take heat as an example. Heat is a corporeal power, _i. e._, a power residing in a body. It extends through the dimensions of the body, and as the latter is divided so is the former. But this is evidently not true of general ideas, such as that a thing cannot both be and not be, that the whole is greater than its part, and so on. Hence the rational power is independent of body.

Ibn Daud gives several other proofs, taken from Aristotle and Avicenna, to show that reason is independent, but we cannot reproduce them all here. We shall, however, name one more which is found in the "De Anima" of Aristotle and is based on experience. If the reason performed its thinking by means of a corporeal organ like the external senses, the power of knowing would be weakened when confronted with a difficult subject, and would thereby be incapacitated from exercising its powers as before. This is the case with the eye, which is dazzled by a bright light and cannot see at all, or the ear, which cannot hear at all when deafened by a loud noise. But the case of knowledge is clearly different. The more difficult the subject the more is the power of the reason developed in exercising itself therein. And in old age, when the corporeal organs are weakened, the power of reason is strongest.

Although it is thus true that the rational soul is independent of the body, nevertheless it did not exist before the body any more than the lower souls. For if it did, it was either one soul for all men, or there were as many souls as there are individual men. The first is impossible; for the same soul would then be wise and ignorant, good and bad, which is impossible. Nor could the separate souls be different, for being all human souls they cannot differ in essence, which is their common humanity. But neither can they differ in accidental qualities, for simple substances have no accidents. They cannot therefore be either one or many, _i. e._, they cannot be at all before body.

Nor must we suppose because the reason exercises its thought functions without the use of a corporeal organ that it appears full fledged in actual perfection in the person of the infant. Experience teaches otherwise. The perfections of the human soul are in the child potential. Later on by divine assistance he acquires the first principles of knowledge about which there is no dispute, such as that two things equal to the same thing are equal to each other, that two contrary predicates cannot apply to the same subject at the same time in the same relation, and so on. Some of these are the fundamental principles of mathematics, others of other sciences. Then he progresses further and learns to make premises and construct syllogisms and argue from the known to the unknown. We have thus three stages in the development of the reason. The first potential stage is known as the _hylic_ or _potential intellect_. The second is known as the _actual intellect_, and the third is the _acquired intellect_. If not for the body the person could not make this progress. For without body there are no senses, and without senses he would not see how the wine in the barrel ferments and increases in volume, which suggests that quantity is accident and body is substance. Nor would he learn the distinction between quality and substance if he did not observe a white garment turning black, or a hot body becoming cold. There is need therefore of the body with its senses to lead to a knowledge of the universals. But this knowledge once acquired, the soul needs not the body for its subsequent existence; and as the soul is not a corporeal power, the death of the body does not cause the extinction of the soul.

Some think that because the soul is the form of the body it is dependent upon it and cannot survive it, as no other form survives its substance. But this inference is not valid. For if the human soul is included in the statement that no form survives its matter, we assume what we want to prove, and there is no need of the argument. If it is not as a matter of fact included, because it is the question at issue, its comparison with the other observed cases is simply a matter of opinion and not decisive.

The reader will see that the problem of the rational soul gave Ibn Daud much concern and trouble. The pre-existence of the soul as Plato teaches it did not appeal to him for many reasons, not the least among them being the statement in Genesis (2, 7), "And God breathed into his nostrils the breath of life," which seems to favor the idea of the soul originating with the body; though, to be sure, a harmless verse of this kind would not have stood in his way, had he had reason to favor the doctrine of pre-existence. Immortality was also a dogma which he dared not deny. The arguments against it seemed rather strong. From the doctrine of the soul's origin with the body and its being fitted to the material composition of the latter, would seem to follow the soul's extinction with the death of the body. The same result was apparently demanded by the observation that the intellect develops as the body matures, and that without the senses and their data there would be no intellect at all. The fluctuation of intellectual strength with the state of bodily health would seem to tend to the same end, against the doctrine of immortality. Moreover, the Aristotelian definition of the soul as the entelechy or form of the body, if it applies to the rational faculty as well as to the lower powers, implies necessarily that it is a form like other forms and disappears with the dissolution of its substance. To avoid all these pitfalls Ibn Daud insists upon the incorporeal character of the reason's activity, _i. e._, its independence of any corporeal organ, and its increasing power in old age despite the gradual weakening of the body. He admits that its development is dependent on the data of sense perception, but insists that this is not incompatible with its freedom from the body when fully developed and perfected. As for its being a form of body, not all forms are alike; and it is not so certain that the rational power is a form of body. Neither the difficulties nor the solution are of Ibn Daud's making. They are as old as Aristotle, and his successors grappled with them as best they could.

There is still the question of the manner of the soul's survival. The same reasons which Ibn Daud brings forward against the possibility of the existence of many souls before the body, apply with equal cogency to their survival after death. If simple substances having a common essence cannot differ either in essence or in accident, the human souls after the death of the body must exist as one soul, and what becomes of _individual_ immortality, which religion promises? Ibn Daud has not a word to say about this, and it is one of the weak points religiously in his system as well as in that of Maimonides, which the critics and opponents of the latter did not fail to observe.

Before leaving the problem of the soul Ibn Daud devotes a word to showing that metempsychosis is impossible. The soul of man is suited to the character of his elemental mixture, which constitutes the individuality of his body. Hence every individual's body has its own peculiar soul. A living person cannot therefore have in him a soul which formerly resided in a different body unless the two bodies are identical in all respects. But in that case it is not transmigration but the re-appearance of the same person after he has ceased to be. But this has never yet happened.

Finally Ibn Daud finds it necessary to defend the Bible against those who criticize the Jews on the ground that there is no mention of the future world and the existence of the soul after death in the Biblical writings. All the rewards and punishments spoken of in the Bible, they say, refer to this world. His answer offers nothing new. Judah Halevi had already tried to account for this phenomenon, besides insisting that altogether devoid of allusion to the future world the Bible is not. Ibn Daud follows in Halevi's footsteps (_cf._ above, p. 170).[236]

Abraham Ibn Daud closes the first, the purely scientific part of his treatise, by a discussion of the heavenly spheres and their motions. In accordance with the view of Aristotle, which was shared by the majority of writers throughout the middle ages, he regards the spheres with their stars as living beings, and their motions as voluntary, the result of will and purpose, and not simply "natural," _i. e._, due to an unconscious force within them called nature. One of his arguments to prove this is derived from the superiority of the heavenly bodies to our own. Their size, their brightness and their continued duration are all evidence of corporeal superiority. And it stands to reason that as the human body, which is the highest in the sublunar world, has a soul that is nobler than that of plant or animal, so the heavenly bodies must be endowed with souls as much superior to the human intellect as their bodies are to the human body. The Bible alludes to this truth in the nineteenth Psalm, "The heavens declare the glory of God.... There is no speech nor language...." The last expression signifies that they praise God with the intellect. There are other passages in the Bible besides, and particularly the first chapter of Ezekiel, which make it clear that the heavenly bodies are living and intelligent beings; not, to be sure, in the sense of taking nourishment and growing and reproducing their kind and making use of five senses, but in the sense of performing voluntary motions and being endowed with intellect.[237]

We have now concluded our preliminary discussion of the scientific principles lying at the basis of Judaism. And our next task is to study the fundamental doctrines of Jewish theology which form the highest object of knowledge, dealing as they do with God and his attributes and his revelation. The first thing to prove then is the existence of God, since we cannot define him. For definition means the designation of the genus or class to which the thing defined belongs, whereas God cannot be put in a class. As the essence of a thing is revealed by its definition, we cannot know God's essence and are limited to a knowledge of his existence.

The principles for this proof we have already given. They are that a thing cannot move itself, and that an actual infinite series is impossible. The argument then proceeds as follows: Nothing can move itself, hence everything that moves is moved by something other than itself. If this is also moving, it must be moved by a third, and so on _ad infinitum_. But an actual infinite series of things moving and being moved is impossible, and unless we ultimately arrive at a first link in this chain, all motion is impossible. Hence there must be a first to account for the motion we observe in the world. This first must not itself be subject to motion, for it would then have to have another before it to make it move, and it would not be the first we supposed it to be. We have thus proved, therefore, the existence of a _primum movens immobile_, a first unmoved mover.

We must now show that this unmoved mover is incorporeal. This we can prove by means of another principle of physics, made clear in the first part. We showed there that a finite body cannot have an infinite power. But God is infinite. For, being immovable, his power is not affected by time. Hence God cannot be body.

This proof, as we said before, is new in Jewish philosophy. In Bahya we found a proof which bears a close resemblance to this one (_cf._ above, p. 87); but the difference is that Bahya argues from being, Ibn Daud from motion. Bahya says if a thing is, some cause must have made it to be, for a thing cannot make itself. As we cannot proceed _ad infinitum_, there must be a first which is the cause of the existence of everything else. The objection here, of course, is that if a thing cannot make itself, how did the first come to be.