Chapter III: Preface (3)

Mais de plus, combien d'excellents philosophes ont démontré que la pensée n'est qu'une faculté de sentir, et que l'âme raisonnable n'est que l'âme sensitive appliquée à contempler les idées, et à raisonner! Ce qui serait prouvé par cela seul que lorsque le sentiment est éteint, la pensée l'est aussi, comme dans l'apoplexie, la léthargie, la catalepsie, etc. Car ceux qui ont avancé que l'âme n'avait pas moins pensé dans les maladies soporeuses, quoiqu'elle ne se souvint pas des idées qu'elle avait eues, ont soutenu une chose ridicule.

Pour ce qui est de ce développement, c'est une folie de perdre le temps à en rechercher le mécanisme. La nature du mouvement nous est aussi inconnue que celle de la matière. Le moyen de découvrir comment il s'y produit, à moins que de ressusciter avec l'auteur de l'Histoire de l'Ame l'ancienne et inintelligible doctrine des formes substantielles! Je suis donc aussi consolé d'ignorer comment la matière, d'inerte et simple, devient active et composée d'organes, que de ne pouvoir regarder le soleil sans verre rouge: et je suis d'aussi bonne composition sur les autres merveilles incompréhensibles de la nature, sur la production du sentiment et de la pensée dans un être qui ne paraissait autrefois à nos yeux bornés qu'un peu de boue.

Qu'on m'accorde seulement que la matière organisée est douée d'un principe moteur, qui seul la différencie de celle qui ne l'est pas (eh! peut-on rien refuser à l'observation la plus incontestable?) et que tout dépend dans les animaux de la diversité de cette organisation, comme je l'ai assez prouvé; c'en est assez pour deviner l'énigme des substances et celle de l'homme. On voit qu'il n'y en a qu'une dans l'univers et que l'homme est la plus parfaite. Il est au singe, aux animaux les plus spirituels, ce que le pendule planétaire de Huygens est à une montre de Julien le Roi. S'il a fallu plus d'instruments, plus de rouages, plus de ressorts pour marquer les mouvements des planètes, que pour marquer les heures, ou les répéter; s'il a fallu plus d'art à Vaucanson pour faire son Fluteur, que pour son Canard, il eût dû en employer encore davantage pour faire un Parleur; machine qui ne peut plus être regardée comme impossible, surtout entre les mains d'un nouveau Prométhée. Il était donc de même nécessaire que la nature employât plus d'art et d'appareil pour faire et entretenir une machine, qui pendant un siècle entier pût marquer tous les battements du coeur et de l'esprit; car si on n'en voit pas au pouls les heures, c'est du moins le baromètre de la chaleur et de la vivacité, par laquelle on peut juger de la nature de l'âme. Je ne me trompe point, le corps humain est une horloge, mais immense, et construite avec tant d'artifice et d'habileté, que si la roue qui sert à marquer les secondes vient à s'arrêter, celle des minutes tourne et va toujours son train, comme la roue des quarts continue de se mouvoir; et ainsi des autres, quand les premières, rouillées, ou dérangées par quelque cause que ce soit, ont interrompu leur marche. Car n'est-ce pas ainsi que l'obstruction de quelques vaisseaux ne suffit pas pour détruire, ou suspendre le fort des mouvements, qui est dans le coeur, comme dans la pièce ouvrière de la machine; puisqu'au contraire les fluides dont le volume est diminué, ayant moins de chemin a faire, le parcourent d'autant plus vite, emportés comme par un nouveau courant, que la force du coeur s'augmente en raison de la résistance qu'il trouve à l'extrémité des vaisseaux? Lorsque le nerf optique seul comprimé ne laisse plus passer l'image des objets, n'est-ce pas ainsi que la privation de la vue n'empêche pas plus l'usage de l'ouïe, que la privation de ce sens, lorsque les fonctions de la portion molle sont interdites, ne suppose celle de l'autre? N'est-ce pas ainsi encore que l'un entend, sans pouvoir dire qu'il entend (si ce n'est après l'attaque du mal) et que l'autre qui n'entend rien, mais dont les nerfs linguaux sont libres dans le cerveau, dit machinalement tous les rêves qui lui passent par la tête? Phénomènes qui ne surprennent point les médecins éclairés. Ils savent à quoi s'en tenir sur la nature de l'homme; et pour le dire en passant: de deux médecins, le meilleur, celui qui mérite le plus de confiance, c'est toujours, à mon avis, celui qui est le plus versé dans la physique, ou la mécanique du corps humain, et qui laissant l'âme et toutes les inquiétudes que cette chimère donne aux sots et aux ignorans, n'est occupé sérieusement que du pur naturalisme.

Laissons donc le prétendu Mr. Charp se moquer des philosophes qui ont regardé les animaux, comme des machines. Que je pense différemment! Je crois que Descartes serait un homme respectable à tous égards, si, né dans un siècle qu'il n'eût pas dû éclairer, il eût connu le prix de l'expérience et de l'observation, et le danger de s'en écarter. Mais il n'est pas moins juste que je fasse ici une authentique réparation à ce grand homme, pour tous ces petits philosophes mauvais plaisants, et mauvais singes de Locke, qui, au lieu de rire impudemment au nez de Descartes, feraient mieux de sentir que sans lui le champ de la philosophie, comme celui du bon esprit sans Newton, serait peut être encore en friche.

Il est vrai que ce célèbre philosophe s'est beaucoup trompé, et personne n'en disconvient. Mais enfin il a connu la nature animale; il a le premier parfaitement démontré que les animaux étaient de pures machines. Or, après une découverte de cette importance et qui suppose autant de sagacité, le moyen, sans ingratitude, de ne pas faire grâce à toutes ses erreurs!

Elles sont à mes yeux toutes réparées par ce grand aveu. Car enfin, quoiqu'il chante sur la distinction des deux substances, il est visible que ce n'est qu'un tour d'adresse, une ruse de style, pour faire avaler aux théologiens un poison caché à l'ombre d'une analogie qui frappe tout le monde, et qu'eux seuls ne voient pas. Car c'est elle, c'est cette forte analogie qui force tous les savants et les vrais juges d'avouer que ces êtres fiers et vains, plus distingués par leur orgueil que par le nom d'hommes, quelque envie qu'ils aient de s'élever, ne sont au fond que des animaux et des machines perpendiculairement rampantes. Elles ont toutes ce merveilleux instinct, dont l'éducation fait de l'esprit, et qui a toujours son siège dans le cerveau, et à son défaut, comme lorsqu'il manque ou est ossifié, dans la moëlle allongée, et jamais dans le cervelet; car je l'ai vu considérablement blessé, d'autres [8] l'ont trouvé squirreux, sans que l'âme cessât de faire ses fonctions.

Etre machine, sentir, penser, savoir distinguer le bien du mal, comme le bleu du jaune, en un mot être né avec de l'intelligence et un instinct sûr de morale, et n'être qu'un animal, sont donc des choses qui ne sont pas plus contradictoires qu'être un singe ou un perroquet et savoir se donner du plaisir. Car, puisque l'occasion se présente de le dire, qui eut jamais deviné à priori qu'une goutte de la liqueur qui se lance dans l'accouplement fit ressentir des plaisirs divins, et qu'il en naîtrait une petite créature, qui pourrait un jour, posées certaines lois, jouir des mêmes délices? Je crois la pensée si peu incompatible avec la matière organisée, qu'elle semble en être une propriété, telle que l'électricité, la faculté motrice, l'impénétrabilité, l'étendue, etc.

Voulez vous de nouvelles observations? En voici qui sont sans réplique et qui prouvent toutes que l'homme ressemble parfaitement aux animaux dans son origine, comme dans tout ce que nous avons déjà cru essentiel de comparer.

J'en appelle à la bonne foi de nos observateurs. Qu'ils nous disent s'il n'est pas vrai que l'homme dans son principe n'est qu'un ver, qui devient homme, comme la chenille papillon. Les plus graves [9] auteurs nous ont appris comment il faut s'y prendre pour voir cet animalcule. Tous les curieux l'ont vu, comme Hartsoeker, dans la semence de l'homme, et non dans celle de la femme; il n'y a que les sots qui s'en soient fait scrupule. Comme chaque goutte de sperme contient une infinité de ces petits vers lorsqu'ils sont lancés à l'ovaire, il n'y a que le plus adroit, ou le plus vigoureux qui ait la force de s'insinuer et de s'implanter dans l'oeuf que fournit la femme, et qui lui donne sa première nourriture. Cet oeuf, quelquefois surpris dans les trompes de Fallope, est porté par ces canaux à la matrice, où il prend racine, comme un grain de blé dans la terre. Mais quoiqu'il y devienne monstrueux par sa croissance de 9 mois, il ne diffère point des oeufs des autres femelles, si ce n'est que sa peau (l'amnios) ne se durcit jamais, et se dilate prodigieusement, comme on en peut juger en comparant les foetus trouvés en situation et près d'éclore (ce que j'ai eu le plaisir d'observer dans une femme morte un moment avant l'accouchement), avec d'autres petits embryons très proches de leur origine: car alors c'est toujours l'oeuf dans sa coque, et l'animal dans l'oeuf, qui, gêné dans ses mouvements, cherche machinalement à voir le jour; et pour y réussir, il commence par rompre avec la tête cette membrane, d'oû il sort, comme le poulet, l'oiseau, etc., de la leur. J'ajouterai une observation que je ne trouve nulle part; c'est que l'amnios n'en est pas plus mince, pour s'être prodigieusement étendu; semblable en cela à la matrice dont la substance même se gonfle de sucs infiltrés, indépendamment de la réplétion et du déploiement de tous ses coudes vasculeux.

Voyons l'homme dans et hors de sa coque; examinons avec un microscope les plus jeunes embryons, de 4, de 6, de 8 ou de 15 jours; après ce temps les yeux suffisent. Que voit-on? la tête seule; un petit oeuf rond avec deux points noirs qui marquent les yeux. Avant ce temps, tout étant plus informe, on n'aperçoit qu'une pulpe médullaire, qui est le cerveau, dans lequel se forme d'abord l'origine des nerfs, ou le principe du sentiment, et le coeur qui a déjà par lui-même dans cette pulpe la faculté de battre: c'est le punctum saliens de Malpighi, qui doit peut-être déjà une partie de sa vivacité à l'influence des nerfs. Ensuite peu-à-peu on voit la tête allonger le col, qui en se dilatant forme d'abord le thorax, où le coeur a déjà descendu, pour s'y fixer; après quoi vient le bas ventre qu'une cloison (le diaphragme) sépare. Ces dilatations donnent l'une, les bras, les mains, les doigts, les ongles, et les poils; l'autre les cuisses, les jambes, les pieds, etc., avec la seule différence de situation qu'on leur connait, qui fait l'appui et le balancier du corps. C'est une végétation frappante. Ici, ce sont des cheveux qui couvrent le sommet de nos têtes; là, ce sont des feuilles et des fleurs. Partout brille le même luxe de la nature; et enfin l'esprit recteur des plantes est placé où nous avons notre âme, cette autre quintessence de l'homme.

Telle est l'uniformité de la nature qu'on commence à sentir, et l'analogie du règne animal et végétal, de l'homme à la plante. Peut-être même y a-t-il des plantes animal, c'est-à-dire qui en végétant, ou se battent comme les polypes, ou font d'autres fonctions propres aux animaux?

Voilà à peu près tout ce qu'on sait de la génération. Que les parties qui s'attirent, qui sont faites pour s'unir ensemble et pour occuper telle ou telle place, se réunissent toutes suivant leur nature; et qu'ainsi se forment les yeux, le coeur, l'estomac et enfin tout le corps, comme de grands hommes l'ont écrit, cela est possible. Mais, comme l'expérience nous abandonne au milieu des ces subtilités, je ne supposerai rien, regardant tout ce qui ne frappe pas mes sens comme un mystère impénétrable. Il est si rare que les deux semences se rencontrent dans le congrès, que je serais tenté de croire que la semence de la femme est inutile à la génération.

Mais comment en expliquer les phénomènes, sans ce commode rapport de parties, qui rend si bien raison des ressemblances des enfants, tantôt au père, et tantôt à la mère? D'un autre côté, l'embarras d'une explication doit-elle contrebalancer un fait? Il me parait que c'est le mâle qui fait tout, dans une femme qui dort, comme dans la plus lubrique. L'arrangement des parties serait donc fait de toute éternité dans le germe, ou dans le ver même de l'homme. Mais tout ceci est fort au-dessus de la portée des plus excellents observateurs. Comme ils n'y peuvent rien saisir, ils ne peuvent pas plus juger de la mécanique de la formation et du développement des corps, qu'une taupe du chemin qu'un cerf peut parcourir.

Nous sommes de vraies taupes dans le champ de la nature; nous n'y faisons guères que le trajet de cet animal; et c'est notre orgueil qui donne des bornes à ce qui n'en a point. Nous sommes dans le cas d'une montre qui dirait: (un fabuliste en ferait un personnage de conséquence dans un ouvrage frivole) "Quoi! c'est ce sot ouvrier qui m'a faite, moi qui divise le temps! moi qui marque si exactement le cours du soleil; moi qui répète à haute voix les heures que j'indique! non, cela ne se peut pas." Nous dédaignons de même, ingrats que nous sommes, cette mère commune de tous les règnes, comme parlent les chimistes. Nous imaginons ou plutôt supposons une cause supérieure à celle à qui nous devons tout, et qui a véritablement tout fait d'une manière inconcevable. Non, la matière n'a rien de vil, qu'aux yeux grossiers qui la méconnaissent dans ses plus brillants ouvrages; et la nature n'est point une ouvrière bornée. Elle produit des millions d'hommes avec plus de facilité et de plaisir, qu'un horloger n'a de peine à faire la montre la plus composée. Sa puissance éclate également et dans la production du plus vil insecte, et dans celle de l'homme le plus superbe; le règne animal ne lui coûte pas plus que le végétal, ni le plus beau génie qu'un épi de blé. Jugeons donc par ce que nous voyons, de ce qui se dérobe à la curiosité de nos yeux et de nos recherches, et n'imaginons rien au delà. Suivons le singe, le castor, l'éléphant, etc., dans leurs opérations. S'il est évident qu'elles ne peuvent se faire sans intelligence, pourquoi la refuser à ces animaux? et si vous leur accordez une âme, fanatiques, vous êtes perdus; vous aurez beau dire que vous ne décidez point sur sa nature, tandis que vous lui ôtez l'immortalité; qui ne voit que c'est une assertion gratuite? qui ne voit qu'elle doit être ou mortelle, ou immortelle, comme la nôtre, dont elle doit subir le même sort quel qu'il soit! et qu'ainsi c'est tomber dans Scilla pour vouloir éviter Caribde?

Brisez la chaîne de vos préjugés; armez-vous du flambeau de l'expérience et vous ferez à la nature l'honneur qu'elle mérite, au lieu de rien conclure à son désavantage, de l'ignorance où elle vous a laissé. Ouvrez les yeux seulement, et laissez-là ce que vous ne pouvez comprendre; et vous verrez que ce laboureur dont l'esprit et les lumières ne s'étendent pas plus loin que les bords de son sillon, ne diffère point essentiellement du plus grand génie, comme l'eût prouvé la dissection des cerveaux de Descartes et de Newton: vous serez persuadé que l'imbécile ou le stupide sont des bêtes à figure humaine, comme le singe plein d'esprit est un petit homme sous une autre forme; et qu'enfin tout dépendant absolument de la diversité de l'organisation, un animal bien construit, à qui on a appris l'astronomie, peut prédire une éclipse, comme la guérison ou la mort, lorsqu'il a porté quelque temps du génie et de bons yeux à l'école d'Hippocrate et au lit des malades. C'est par cette file d'observations et de vérités qu'on parvient à lier à la matière l'admirable propriété de penser, sans qu'on en puisse voir les liens, parce que le sujet de cet attribut nous est essentiellement inconnu.

Ne disons point que toute machine, ou tout animal, périt tout-à-fait, ou prend une autre forme, après la mort; car nous n'en savons absolument rien. Mais assurer qu'une machine immortelle est une chimère, ou un être de raison, c'est faire un raisonnement aussi absurde que celui que feraient des chenilles, qui, voyant les dépouilles de leurs semblables, déploreraient amèrement le sort de leur espèce qui leur semblerait s'anéantir. L'âme de ces insectes (car chaque animal a la sienne) est trop bornée pour comprendre les métamorphoses de la nature. Jamais un seul des plus rusés d'entr'eux n'eût imaginé qu'il dût devenir papillon. Il en est de même de nous. Que savons-nous plus de notre destinée, que de notre origine? Soumettons-nous donc à une ignorance invincible de laquelle notre bonheur dépend.

Qui pensera ainsi, sera sage, juste, tranquille sur son sort, et par conséquent heureux. Il attendra la mort, sans la craindre, ni la désirer; et chérissant la vie, comprenant à peine comment le dégoût vient corrompre un coeur dans ce lieu plein de délices; plein de respect pour la nature, plein de reconnaissance, d'attachement et de tendresse, à proportion du sentiment et des bienfaits qu'il en a reçus, heureux enfin de la sentir, et d'être au charmant spectacle de l'univers, il ne le détruira certainement jamais dans soi, ni dans les autres. Que dis-je! plein d'humanité, il en aimera le caractère jusques dans ses ennemis. Jugez comme il traitera les autres! Il plaindra les vicieux, sans les haïr; ce ne seront à ses yeux que des hommes contrefaits. Mais en faisant grâce aux défauts de la conformation de l'esprit et du corps, il n'en admirera pas moins leurs beautés et leurs vertus. Ceux que la nature aura favorisés lui paraîtront mériter plus d'égards que ceux qu'elle aura traités en marâtre. C'est ainsi qu'on a vu que les dons naturels, la source de tout ce qui s'acquiert, trouvent dans la bouche et le coeur du matérialiste des hommages que tout autre leur refuse injustement. Enfin le matérialiste convaincu, quoi que murmure sa propre vanité, qu'il n'est qu'une machine, ou un animal, ne maltraitera point ses semblables; trop instruit sur la nature de ces actions, dont l'inhumanité est toujours proportionnée au degré d'analogie prouvée ci devant; et ne voulant pas en un mot, suivant la loi naturelle donnée à tous les animaux, faire à autrui ce qu'il ne voudrait pas qu'il lui fît.

Concluons donc hardiment que l'homme est une machine; et qu'il n'y a dans tout l'univers qu'une seule substance diversement modifiée. Ce n'est point ici une hypothèse élevée à force de demandes et de suppositions: ce n'est point l'ouvrage du préjugé, ni même de ma raison seule; j'eusse dédaigné un guide que je crois si peu sûr, si mes sens portant, pour ainsi dire, le flambeau, ne m'eûssent engagé à la suivre, en l'éclairant. L'expérience m'a donc parlé pour la raison; c'est ainsi que je les ai jointes ensemble.

Mais on a dû voir que je ne me suis permis le raisonnement le plus rigoureux et le plus immédiatement tiré, qu'à la suite d'une multitude d'observations physiques qu'aucun savant ne contestera; et c'est encore eux seuls que je reconnais pour juges des conséquences que j'en tire; récusant ici tout homme à préjugés, et qui n'est ni anatomiste, ni au fait de la seule philosophie qui soit ici de mise, celle du corps humain. Que pourraient contre un chêne aussi ferme et solide ces faibles roseaux de la théologie, de la métaphysique et des écoles; armes puériles, semblables aux fleurets de nos salles, qui peuvent bien donner le plaisir de l'escrime, mais jamais entamer son adversaire. Faut-il dire que je parle de ces idées creuses et triviales, de ces raisonnements rebattus et pitoyables, qu'on fera sur la prétendue incompatibilité de deux substances qui se touchent et se remuent sans cesse l'une et l'autre, tant qu'il restera l'ombre du préjugé ou de la superstition sur la terre? Voilà mon système, ou plutôt la vérité, si je ne me trompe fort. Elle est courte et simple. Dispute à présent qui voudra!

MAN A MACHINE.

It is not enough for a wise man to study nature and truth; he should dare state truth for the benefit of the few who are willing and able to think. As for the rest, who are voluntarily slaves of prejudice, they can no more attain truth, than frogs can fly.

I reduce to two the systems of philosophy which deal with man's soul. The first and older system is materialism; the second is spiritualism.

The metaphysicians who have hinted that matter may well be endowed with the faculty of thought{1} have perhaps not reasoned ill. For there is in this case a certain advantage in their inadequate way of expressing their meaning. In truth, to ask whether matter can think, without considering it otherwise than in itself, is like asking whether matter can tell time. It may be foreseen that we shall avoid this reef upon which Locke had the bad luck to make shipwreck.

The Leibnizians with their monads have set up an unintelligible hypothesis. They have rather spiritualized matter than materialized the soul. How can we define a being whose nature is absolutely unknown to us?{2}

Descartes and all the Cartesians, among whom the followers of Malebranche have long been numbered, have made the same mistake. They have taken for granted two distinct substances in man, as if they had seen them, and positively counted them.

The wisest men have declared that the soul can not know itself save by the light of faith. However, as reasonable beings they have thought that they could reserve for themselves the right of examining what the Bible means by the word "spirit," which it uses in speaking of the human soul. And if in their investigation, they do not agree with the theologians on this point, are the theologians more in agreement among themselves on all other points?

Here is the result in a few words, of all their reflections. If there is a God, He is the Author of nature as well as of revelation. He has given us the one to explain the other, and reason to make them agree.

To distrust the knowledge that can be drawn from the study of animated bodies, is to regard nature and revelation as two contraries which destroy each the other, and consequently to dare uphold the absurd doctrine, that God contradicts Himself in His various works and deceives us.

If there is a revelation, it can not then contradict nature. By nature only can we understand the meaning of the words of the Gospel, of which experience is the only true interpreter. In fact, the commentators before our time have only obscured the truth. We can judge of this by the author of the "Spectacle of Nature."{3} "It is astonishing," he says concerning Locke, "that a man who degrades our soul far enough to consider it a soul of clay should dare set up reason as judge and sovereign arbiter of the mysteries of faith, for," he adds, "what an astonishing idea of Christianity one would have, if one were to follow reason."

Not only do these reflections fail to elucidate faith, but they also constitute such frivolous objections to the method of those who undertake to interpret the Scripture, that I am almost ashamed to waste time in refuting them.

The excellence of reason does not depend on a big word devoid of meaning (immateriality), but on the force, extent, and perspicuity of reason itself. Thus a "soul of clay" which should discover, at one glance, as it were, the relations and the consequences of an infinite number of ideas hard to understand, would evidently be preferable to a foolish and stupid soul, though that were composed of the most precious elements. A man is not a philosopher because, with Pliny, he blushes over the wretchedness of our origin. What seems vile is here the most precious of things, and seems to be the object of nature's highest art and most elaborate care. But as man, even though he should come from an apparently still more lowly source, would yet be the most perfect of all beings, so whatever the origin of his soul, if it is pure, noble, and lofty, it is a beautiful soul which dignifies the man endowed with it.

Pluche's second way of reasoning seems vicious to me, even in his system, which smacks a little of fanaticism; for [on his view] if we have an idea of faith as being contrary to the clearest principles, to the most incontestable truths, we must yet conclude, out of respect for revelation and its author, that this conception is false, and that we do not yet understand the meaning of the words of the Gospel.

Of the two alternatives, only one is possible: either everything is illusion, nature as well as revelation, or experience alone can explain faith. But what can be more ridiculous than the position of our author! Can one imagine hearing a Peripatetic say, "We ought not to accept the experiments of Torricelli,{4} for if we should accept them, if we should rid ourselves of the horror of the void, what an astonishing philosophy we should have!"

I have shown how vicious the reasoning of Pluche is [10] in order to prove, in the first place, that if there is a revelation, it is not sufficiently demonstrated by the mere authority of the Church, and without any appeal to reason, as all those who fear reason claim: and in the second place, to protect against all assault the method of those who would wish to follow the path that I open to them, of interpreting supernatural things, incomprehensible in themselves, in the light of those ideas with which nature has endowed us. Experience and observation should therefore be our only guides here. Both are to be found throughout the records of the physicians who were philosophers, and not in the works of the philosophers who were not physicians. The former have traveled through and illuminated the labyrinth of man; they alone have laid bare to us those springs [of life] hidden under the external integument which conceals so many wonders from our eyes. They alone, tranquilly contemplating our soul, have surprised it, a thousand times, both in its wretchedness and in its glory, and they have no more despised it in the first estate, than they have admired it in the second. Thus, to repeat, only the physicians have a right to speak on this subject.{5} What could the others, especially the theologians, have to say? Is it not ridiculous to hear them shamelessly coming to conclusions about a subject concerning which they have had no means of knowing anything, and from which on the contrary they have been completely turned aside by obscure studies that have led them to a thousand prejudiced opinions,--in a word, to fanaticism, which adds yet more to their ignorance of the mechanism of the body?

But even though we have chosen the best guides, we shall still find many thorns and stumbling blocks in the way.

Man is so complicated a machine{6} that it is impossible to get a clear idea of the machine beforehand, and hence impossible to define it. For this reason, all the investigations have been vain, which the greatest philosophers have made à priori, that is to say, in so far as they use, as it were, the wings of the spirit. Thus it is only à posteriori or by trying to disentangle the soul from the organs of the body, so to speak, that one can reach the highest probability concerning man's own nature, even though one can not discover with certainty what his nature is.

Let us then take in our hands the staff of experience,{7} paying no heed to the accounts of all the idle theories of philosophers. To be blind and to think that one can do without this staff is the worst kind of blindness. How truly a contemporary writer says that only vanity fails to gather from secondary causes the same lessons as from primary causes! One can and one even ought to admire all these fine geniuses in their most useless works, such men as Descartes, Malebranche, Leibniz, Wolff and the rest, but what profit, I ask, has any one gained from their profound meditations, and from all their works? Let us start out then to discover not what has been thought, but what must be thought for the sake of repose in life.

There are as many different minds, different characters, and different customs, as there are different temperaments. Even Galen{8} knew this truth which Descartes carried so far as to claim that medicine alone can change minds and morals, along with bodies. (By the writer of "L'histoire de l'âme,"{9} this teaching is incorrectly attributed to Hippocrates.{10}) It is true that melancholy, bile, phlegm, blood etc.--according to the nature, the abundance, and the different combination of these humors--make each man different from another.{11}

In disease the soul is sometimes hidden, showing no sign of life; sometimes it is so inflamed by fury that it seems to be doubled; sometimes, imbecility vanishes and the convalescence of an idiot produces a wise man. Sometimes, again, the greatest genius becomes imbecile and loses the sense of self. Adieu then to all that fine knowledge, acquired at so high a price, and with so much trouble! Here is a paralytic who asks if his leg is in bed with him; there is a soldier who thinks that he still has the arm which has been cut off. The memory of his old sensations, and of the place to which they were referred by his soul, is the cause of his illusion, and of this kind of delirium. The mere mention of the member which he has lost is enough to recall it to his mind, and to make him feel all its motions; and this causes him an indefinable and inexpressible kind of imaginary suffering. This man cries like a child at death's approach, while this other jests. What was needed to change the bravery of Caius Julius, Seneca, or Petronius into cowardice or faintheartedness? Merely an obstruction in the spleen, in the liver, an impediment in the portal vein? Why? Because the imagination is obstructed along with the viscera, and this gives rise to all the singular phenomena of hysteria and hypochondria.

What can I add to the stories already told of those who imagine themselves transformed into wolf-men, cocks or vampires, or of those who think that the dead feed upon them? Why should I stop to speak of the man who imagines that his nose or some other member is of glass? The way to help this man regain his faculties and his own flesh-and-blood nose is to advise him to sleep on hay, lest he break the fragile organ, and then to set fire to the hay that he may be afraid of being burned--a fear which has sometimes cured paralysis. But I must touch lightly on facts which everybody knows.

Neither shall I dwell long on the details of the effects of sleep. Here a tired soldier snores in a trench, in the middle of the thunder of hundreds of cannon. His soul hears nothing; his sleep is as deep as apoplexy. A bomb is on the point of crushing him. He will feel this less perhaps than he feels an insect which is under his foot.

On the other hand, this man who is devoured by jealousy, hatred, avarice, or ambition, can never find any rest. The most peaceful spot, the freshest and most calming drinks are alike useless to one who has not freed his heart from the torment of passion.

The soul and the body fall asleep together. As the motion of the blood is calmed, a sweet feeling of peace and quiet spreads through the whole mechanism. The soul feels itself little by little growing heavy as the eyelids droop, and loses its tenseness, as the fibres of the brain relax; thus little by little it becomes as if paralyzed and with it all the muscles of the body. These can no longer sustain the weight of the head, and the soul can no longer bear the burden of thought; it is in sleep as if it were not.

Is the circulation too quick? the soul can not sleep. Is the soul too much excited? the blood can not be quieted: it gallops through the veins with an audible murmur. Such are the two opposite causes of insomnia. A single fright in the midst of our dreams makes the heart beat at double speed and snatches us from needed and delicious repose, as a real grief or an urgent need would do. Lastly as the mere cessation of the functions of the soul produces sleep, there are, even when we are awake (or at least when we are half awake), kinds of very frequent short naps of the mind, vergers' dreams, which show that the soul does not always wait for the body to sleep. For if the soul is not fast asleep, it surely is not far from sleep, since it can not point out a single object to which it has attended, among the uncounted number of confused ideas which, so to speak, fill the atmosphere of our brains like clouds.

Opium is too closely related to the sleep it produces, to be left out of consideration here. This drug intoxicates, like wine, coffee, etc., each in its own measure and according to the dose.{12} It makes a man happy in a state which would seemingly be the tomb of feeling, as it is the image of death. How sweet is this lethargy! The soul would long never to emerge from it. For the soul has been a prey to the most intense sorrow, but now feels only the joy of suffering past, and of sweetest peace. Opium even alters the will, forcing the soul which wished to wake and to enjoy life, to sleep in spite of itself. I shall omit any reference to the effect of poisons.

Coffee, the well-known antidote for wine, by scourging the imagination, cures our headaches and scatters our cares without laying up for us, as wine does, other headaches for the morrow. But let us contemplate the soul in its other needs.

The human body is a machine which winds its own springs. It is the living image of perpetual movement. Nourishment keeps up the movements which fever excites. Without food, the soul pines away, goes mad, and dies exhausted. The soul is a taper whose light flares up the moment before it goes out. But nourish the body, pour into its veins life-giving juices and strong liquors, and then the soul grows strong like them, as if arming itself with a proud courage, and the soldier whom water would have made flee, grows bold and runs joyously to death to the sound of drums. Thus a hot drink sets into stormy movement the blood which a cold drink would have calmed.

What power there is in a meal! Joy revives in a sad heart, and infects the souls of comrades, who express their delight in the friendly songs in which the Frenchman excels. The melancholy man alone is dejected, and the studious man is equally out of place [in such company].

Raw meat makes animals fierce, and it would have the same effect on man. This is so true that the English who eat meat red and bloody, and not as well done as ours, seem to share more or less in the savagery due to this kind of food, and to other causes which can be rendered ineffective by education only. This savagery creates in the soul, pride, hatred, scorn of other nations, indocility and other sentiments which degrade the character, just as heavy food makes a dull and heavy mind whose usual traits are laziness and indolence.

Pope understood well the full power of greediness when he said:{13}

"Catius is ever moral, ever grave,
Thinks who endures a knave is next a knave,
Save just at dinner--then prefers no doubt,
A rogue with ven'son to a saint without."

Elsewhere he says:

"See the same man in vigor, in the gout
Alone, in company, in place or out,
Early at business and at hazard late,
Mad at a fox chase, wise at a debate,
Drunk at a borough, civil at a ball,
Friendly at Hackney, faithless at White Hall."

In Switzerland we had a bailiff by the name of M. Steigner de Wittighofen. When he fasted he was a most upright and even a most indulgent judge, but woe to the unfortunate man whom he found on the culprit's bench after he had had a large dinner! He was capable of sending the innocent like the guilty to the gallows.

We think we are, and in fact we are, good men, only as we are gay or brave; everything depends on the way our machine is running. One is sometimes inclined to say that the soul is situated in the stomach, and that Van Helmont,{14} who said that the seat of the soul was in the pylorus, made only the mistake of taking the part for the whole.

To what excesses cruel hunger can bring us! We no longer regard even our own parents and children. We tear them to pieces eagerly and make horrible banquets of them; and in the fury with which we are carried away, the weakest is always the prey of the strongest....

One needs only eyes to see the necessary influence of old age on reason. The soul follows the progress of the body, as it does the progress of education. In the weaker sex, the soul accords also with delicacy of temperament, and from this delicacy follow tenderness, affection, quick feelings due more to passion than to reason, prejudices, and superstitions, whose strong impress can hardly be effaced. Man, on the other hand, whose brain and nerves partake of the firmness of all solids, has not only stronger features but also a more vigorous mind. Education, which women lack, strengthens his mind still more. Thus with such help of nature and art, why should not a man be more grateful, more generous, more constant in friendship, stronger in adversity? But, to follow almost exactly the thought of the author of the "Lettres sur la Physiognomie,"{15} the sex which unites the charms of the mind and of the body with almost all the tenderest and most delicate feelings of the heart, should not envy us the two capacities which seem to have been given to man, the one merely to enable him better to fathom the allurements of beauty, and the other merely to enable him to minister better to its pleasures.

It is no more necessary to be just as great a physiognomist as this author, in order to guess the quality of the mind from the countenance or the shape of the features, provided these are sufficiently marked, than it is necessary to be a great doctor to recognize a disease accompanied by all its marked symptoms. Look at the portraits of Locke, of Steele, of Boerhaave,{16} of Maupertuis,{17} and the rest, and you will not be surprised to find strong faces and eagle eyes. Look over a multitude of others, and you can always distinguish the man of talent from the man of genius, and often even an honest man from a scoundrel. For example, it has been noticed that a celebrated poet combines (in his portrait) the look of a pickpocket with the fire of Prometheus.

History provides us with a noteworthy example of the power of temperature. The famous Duke of Guise was so strongly convinced that Henry the Third, in whose power he had so often been, would never dare assassinate him, that he went to Blois. When the Chancelor Chiverny learned of the duke's departure, he cried, "He is lost." After this fatal prediction had been fulfilled by the event, Chiverny was asked why he made it. "I have known the king for twenty years," said he; "he is naturally kind and even weakly indulgent, but I have noticed that when it is cold, it takes nothing at all to provoke him and send him into a passion."

One nation is of heavy and stupid wit, and another quick, light and penetrating. Whence comes this difference, if not in part from the difference in foods, and difference in inheritance, [11] and in part from the mixture of the diverse elements which float around in the immensity of the void? The mind, like the body, has its contagious diseases and its scurvy.

Such is the influence of climate, that a man who goes from one climate to another, feels the change, in spite of himself. He is a walking plant which has transplanted itself; if the climate is not the same, it will surely either degenerate or improve.

Furthermore, we catch everything from those with whom we come in contact; their gestures, their accent, etc.; just as the eyelid is instinctively lowered when a blow is foreseen, or as (for the same reason) the body of the spectator mechanically imitates, in spite of himself, all the motions of a good mimic.{18}

From what I have just said, it follows that a brilliant man is his own best company, unless he can find other company of the same sort. In the society of the unintelligent, the mind grows rusty for lack of exercise, as at tennis a ball that is served badly is badly returned. I should prefer an intelligent man without an education, if he were still young enough, to a man badly educated. A badly trained mind is like an actor whom the provinces have spoiled.

Thus, the diverse states of the soul are always correlative with those of the body.{19} But the better to show this dependence, in its completeness and its causes, let us here make use of comparative anatomy; let us lay bare the organs of man and of animals. How can human nature be known, if we may not derive any light from an exact comparison of the structure of man and of animals?

In general, the form and the structure of the brains of quadrupeds are almost the same as those of the brain of man; the same shape, the same arrangement everywhere, with this essential difference, that of all the animals man is the one whose brain is largest, and, in proportion to its mass, more convoluted than the brain of any other animal; then come the monkey, the beaver, the elephant, the dog, the fox, the cat. These animals are most like man, for among them, too, one notes the same progressive analogy in relation to the corpus callosum in which Lancisi--anticipating the late M. de la Peyronie{20}--established the seat of the soul. The latter, however, illustrated the theory by innumerable experiments. Next after all the quadrupeds, birds have the largest brains. Fish have large heads, but these are void of sense, like the heads of many men. Fish have no corpus callosum, and very little brain, while insects entirely lack brain.

I shall not launch out into any more detail about the varieties of nature, nor into conjectures concerning them, for there is an infinite number of both, as any one can see by reading no further than the treatises of Willis "De Cerebro" and "De Anima Brutorum."{21}

I shall draw the conclusions which follow clearly from these incontestable observations: 1st, that the fiercer animals are, the less brain they have; 2d, that this organ seems to increase in size in proportion to the gentleness of the animal; 3d, that nature seems here eternally to impose a singular condition, that the more one gains in intelligence the more one loses in instinct. Does this bring gain or loss?

Do not think, however, that I wish to infer by that, that the size alone of the brain, is enough to indicate the degree of tameness in animals: the quality must correspond to the quantity, and the solids and liquids must be in that due equilibrium which constitutes health.

If, as is ordinarily observed, the imbecile does not lack brain, his brain will be deficient in its consistency--for instance, in being too soft. The same thing is true of the insane, and the defects of their brains do not always escape our investigation. But if the causes of imbecility, insanity, etc., are not obvious, where shall we look for the causes of the diversity of all minds? They would escape the eyes of a lynx and of an argus. A mere nothing, a tiny fibre, something that could never be found by the most delicate anatomy, would have made of Erasmus and Fontenelle{22} two idiots, and Fontenelle himself speaks of this very fact in one of his best dialogues.

Willis has noticed in addition to the softness of the brain-substance in children, puppies, and birds, that the corpora striata are obliterated and discolored in all these animals, and that the striations are as imperfectly formed as in paralytics....

However cautious and reserved one may be about the consequences that can be deduced from these observations, and from many others concerning the kind of variation in the organs, nerves, etc., [one must admit that] so many different varieties can not be the gratuitous play of nature. They prove at least the necessity for a good and vigorous physical organization, since throughout the animal kingdom the soul gains force with the body and acquires keenness, as the body gains strength.

Let us pause to contemplate the varying capacity of animals to learn. Doubtless the analogy best framed leads the mind to think that the causes we have mentioned produce all the difference that is found between animals and men, although we must confess that our weak understanding, limited to the coarsest observations, can not see the bonds that exist between cause and effects. This is a kind of harmony that philosophers will never know.

Among animals, some learn to speak and sing; they remember tunes, and strike the notes as exactly as a musician. Others, for instance the ape, show more intelligence, and yet can not learn music. What is the reason for this, except some defect in the organs of speech? But is this defect so essential to the structure that it could never be remedied? In a word, would it be absolutely impossible to teach the ape a language?{23} I do not think so.

I should choose a large ape in preference to any other, until by some good fortune another kind should be discovered, more like us, for nothing prevents there being such an one in regions unknown to us. The ape resembles us so strongly that naturalists have called it "wild man" or "man of the woods." I should take it in the condition of the pupils of Amman,{24} that is to say, I should not want it to be too young or too old; for apes that are brought to Europe are usually too old. I would choose the one with the most intelligent face, and the one which, in a thousand little ways, best lived up to its look of intelligence. Finally not considering myself worthy to be his master, I should put him in the school of that excellent teacher whom I have just named, or with another teacher equally skilful, if there is one.

You know by Amman's work, and by all those [12] who have interpreted his method, all the wonders he has been able to accomplish for those born deaf. In their eyes he discovered ears, as he himself explains, and in how short a time! In short he taught them to hear, speak, read, and write. I grant that a deaf person's eyes see more clearly and are keener than if he were not deaf, for the loss of one member or sense can increase the strength or acuteness of another, but apes see and hear, they understand what they hear and see, and grasp so perfectly the signs that are made to them, that I doubt not that they would surpass the pupils of Amman in any other game or exercise. Why then should the education of monkeys be impossible? Why might not the monkey, by dint of great pains, at last imitate after the manner of deaf mutes, the motions necessary for pronunciation? I do not dare decide whether the monkey's organs of speech, however trained, would be incapable of articulation. But, because of the great analogy between ape and man{25} and because there is no known animal whose external and internal organs so strikingly resemble man's, it would surprise me if speech were absolutely impossible to the ape. Locke, who was certainly never suspected of credulity, found no difficulty in believing the story told by Sir William Temple{26} in his memoirs, about a parrot which could answer rationally, and which had learned to carry on a kind of connected conversation, as we do. I know that people have ridiculed [13] this great metaphysician; but suppose some one should have announced that reproduction sometimes takes place without eggs or a female, would he have found many partisans? Yet M. Trembley{27} has found cases where reproduction takes place without copulation and by fission. Would not Amman too have passed for mad if he had boasted that he could instruct scholars like his in so short a time, before he had happily accomplished the feat? His successes have, however, astonished the world; and he, like the author of "The History of Polyps," has risen to immortality at one bound. Whoever owes the miracles that he works to his own genius surpasses, in my opinion, the man who owes his to chance. He who has discovered the art of adorning the most beautiful of the kingdoms [of nature], and of giving it perfections that it did not have, should be rated above an idle creator of frivolous systems, or a painstaking author of sterile discoveries. Amman's discoveries are certainly of a much greater value; he has freed men from the instinct to which they seemed to be condemned, and has given them ideas, intelligence, or in a word, a soul which they would never have had. What greater power than this!

Let us not limit the resources of nature; they are infinite, especially when reinforced by great art.

Could not the device which opens the Eustachian canal of the deaf, open that of apes? Might not a happy desire to imitate the master's pronunciation, liberate the organs of speech in animals that imitate so many other signs with such skill and intelligence? Not only do I defy any one to name any really conclusive experiment which proves my view impossible and absurd; but such is the likeness of the structure and functions of the ape to ours that I have very little doubt that if this animal were properly trained he might at last be taught to pronounce, and consequently to know, a language. Then he would no longer be a wild man, nor a defective man, but he would be a perfect man, a little gentleman, with as much matter or muscle as we have, for thinking and profiting by his education.

The transition from animals to man is not violent, as true philosophers will admit. What was man before the invention of words and the knowledge of language?{28} An animal of his own species with much less instinct than the others. In those days, he did not consider himself king over the other animals, nor was he distinguished from the ape, and from the rest, except as the ape itself differs from the other animals, i. e., by a more intelligent face. Reduced to the bare intuitive knowledge of the Leibnizians he saw only shapes and colors, without being able to distinguish between them: the same, old as young, child at all ages, he lisped out his sensations and his needs, as a dog that is hungry or tired of sleeping, asks for something to eat, or for a walk.

Words, languages, laws, sciences, and the fine arts have come, and by them finally the rough diamond of our mind has been polished. Man has been trained in the same way as animals. He has become an author, as they became beasts of burden. A geometrician has learned to perform the most difficult demonstrations and calculations, as a monkey has learned to take his little hat off and on, and to mount his tame dog. All has been accomplished through signs, every species has learned what it could understand, and in this way men have acquired symbolic knowledge, still so called by our German philosophers.

Nothing, as any one can see, is so simple as the mechanism of our education. Everything may be reduced to sounds or words that pass from the mouth of one through the ears of another into his brain. At the same moment, he perceives through his eyes the shape of the bodies of which these words are the arbitrary signs.

But who was the first to speak? Who was the first teacher of the human race? Who invented the means of utilizing the plasticity of our organism? I can not answer: the names of these first splendid geniuses have been lost in the night of time. But art is the child of nature, so nature must have long preceded it.