It will not, I trust, be unwelcome to you, candid reader, if I yield to the wishes, I might even say the entreaties, of many, and in these Exercises on Animal Generation, lay before the student and lover of truth what I have observed on this subject from anatomical dissections, which turns out to be very different from anything that is delivered by authors, whether philosophers or physicians.
Physicians, following Galen, teach that from the semen of the male and female mingled in coition the offspring is produced, and resembles one or other, according to the predominance of this one or of that; and farther, that in virtue of the same predominance, it is either male or female. Sometimes they declare the semen masculinum as the efficient cause, and the semen femininum as supplying the matter; and sometimes, again, they advocate precisely the opposite doctrine. Aristotle, one of Nature’s most diligent inquirers, however affirms the principles of generation to be the male and the female, she contributing the matter, he the form; and that immediately after the sexual act the vital principle and the first particle of the future fœtus, viz. the heart, in animals that have red blood, are formed from the menstrual blood in the uterus.
But that these are erroneous and hasty conclusions is easily made to appear: like phantoms of darkness they suddenly vanish before the light of anatomical inquiry. Nor is any long refutation necessary where the truth can be seen with one’s proper eyes; where the inquirer by simple inspection finds everything in conformity with reason; and where at the same time he is made to understand how unsafe, how base a thing it is to receive instruction from others’ comments without examination of the objects themselves, the rather as the book of Nature lies so open and is so easy of consultation.
What I shall deliver in these my Exercises on Animal Generation I am anxious to make publicly known, not merely that posterity may there perceive the sure and obvious truth, but farther, and especially, that by exhibiting the method of investigation which I have followed, I may propose to the studious a new and, unless I mistake, a safer way to the attainment of knowledge.
For although it is a new and difficult road in studying nature, rather to question things themselves than, by turning over books, to discover the opinions of philosophers regarding them, still it must be acknowledged that it is the more open path to the secrets of natural philosophy, and that which is less likely to lead into error.
Nor is there any just cause wherefore the labour should deter any one, if he will but think that he himself only lives through the ceaseless working of his heart. Neither, indeed, would the way I propose be felt as so barren and lonely, but for the custom, or vice rather, of the age we live in, when men, inclined to idleness, prefer going wrong with the many, to becoming wise with the few through dint of toil and outlay of money. The ancient philosophers, whose industry even we admire, went a different way to work, and by their unwearied labour and variety of experiments, searching into the nature of things, have left us no doubtful light to guide us in our studies. In this way it is that almost everything we yet possess of note or credit in philosophy, has been transmitted to us through the industry of ancient Greece. But when we acquiesce in the discoveries of the ancients, and believe (which we are apt to do through indolence) that nothing farther remains to be known, we suffer the edge of our ingenuity to be taken off, and the lamp which they delivered to us to be extinguished. No one of a surety will allow that all truth was engrossed by the ancients, unless he be utterly ignorant (to pass by other arts for the present) of the many remarkable discoveries that have lately been made in anatomy, these having been principally achieved by individuals who, either intent upon some particular matter, fell upon the novelty by accident, or (and this is the more excellent way) who following the traces of nature with their own eyes, pursued her through devious but most assured ways till they reached her in the citadel of truth. And truly in such pursuits it is sweet not merely to toil, but even to grow weary, when the pains of discovering are amply compensated by the pleasures of discovery. Eager for novelty, we are wont to travel far into unknown countries, that with our own eyes we may witness what we have heard reported as having been seen by others, where, however, we for the most part find
---- minuit præsentia famam:
that the presence lessens the repute. It were disgraceful, therefore, with this most spacious and admirable realm of nature before us, and where the reward ever exceeds the promise, did we take the reports of others upon trust, and go on coining crude problems out of these, and on them hanging knotty and captious and petty disputations. Nature is herself to be addressed; the paths she shows us are to be boldly trodden; for thus, and whilst we consult our proper senses, from inferior advancing to superior levels, shall we penetrate at length into the heart of her mystery.
Of the Manner and Order of acquiring Knowledge.
Although there is but one road to science, that to wit, in which we proceed from things more known to things less known, from matters more manifest to matters more obscure; and universals are principally known to us, science springing by reasonings from universals to particulars; still the comprehension of universals by the understanding is based upon the perception of individual things by the senses. Both of Aristotle’s propositions, therefore, are true: First, the one in his Physics,[122] where he says, “The way is naturally prepared, from those things that are more obvious and clear to us, to those things that are more obvious and clear by nature. For, indeed, the same things are not both known to us and extant simply: whence it is indispensable to proceed in this way, viz. from those things that are of a more obscure nature, but to us are more apparent, to those that are of a nature more obvious and distinct. Now those things are, in the first instance, more perspicuous and manifest to us that are most confused in fact; whence it is necessary to proceed from universals to particulars; for the whole, according to the dictates of sense, is the more obvious; and the universal is a certain whole.” And again, that other in his Analytics,[123] where he thus expresses himself: “Singulars are to us more known, and are the first that exist according to the information of sense; for, indeed, there is nothing in the understanding which was not first in the sense. And although that reasoning is naturally prior and more known which proceeds by syllogism, still is that more perspicuous to us which is based on induction. And therefore do we more readily define singulars than universals, for there is more of equivocation in universals: whence it is advisable from singulars to pass to universals.”
All this agrees with what we have previously said, although at first blush it may seem contradictory; inasmuch as universals are first imbibed from particulars by the senses, and in so far are only known to us as an universal is a certain whole and indistinct thing, and a whole is known to us according to sense. For though in all knowledge we begin from sense, because, as the philosopher quoted has it, sensible particulars are better known to sense, still the sensation itself is an universal thing. For, if you observe rightly, although in the external sense the object perceived is singular, as, for example, the colour which we call yellow in the eye, still when this impression comes to be made an abstraction, and to be judged of and understood by the internal sensorium, it is an universal. Whence it happens that several persons abstract several species, and conceive different notions, from viewing the same object at the same time. This is conspicuous among poets and painters, who, although they contemplate one and the same object in the same place at the same moment, and with all other circumstances agreeing, nevertheless regard and describe it variously, and as each has conceived or formed an idea of it in his imagination. In the same way, the painter having a certain portrait to delineate, if he draw the outline a thousand times, he will still give a different face, and each not only differing from the other, but from the original countenance; with such slight variety, however, that looking at them singly, you shall conceive you have still the same portrait set before you, although, when set side by side, you perceive how different they are. Now the reason is this: that in vision, or the act of seeing itself, each particular is clear and distinct; but the moment the object is removed, as it is by merely shutting the eyes, when it becomes an abstraction in the fancy, or is only retained in the memory, it appears obscure and indistinct; neither is it any longer apprehended as a particular, but as a something that is common and universal. Seneca[124] explains this subtlety, according to Plato’s views, in very elegant terms: “An idea,” he says, “is an eternal copy of the things that have place in nature. I add an explanation of this definition, that the matter may be made plainer to you. I desire to take your portrait; I have you as the prototype of the picture, from which my mind takes a certain impression which it transfers to the canvass. The countenance, therefore, which teaches and directs me, and from which the imitation is sought, is the idea.” A little farther on he proceeds: “I have but just made use of the image which a painter forms in his mind, by way of illustration. Now, if he would paint a likeness of Virgil, he forms an intuitive image of his subject: the idea is the face of Virgil, the type of his future work; and this which the artist conveys and transfers to his work is the resemblance or portrait. What difference is there? you ask: the one is the pattern or prototype, the other the form taken from the pattern and fixed in the work; the artist imitates the one, he creates the other. A statue has a certain expression of face; this is the Eidos, the species or representation; the prototype himself has a certain expression, which the statuary conceiving, transfers to his statue: this is the idea. Do you desire yet another illustration of the distinction? The Eidos is in the work; the idea without the work, and not only without the work, but it even existed before the work was begun.” For the things that have formerly been noted, and that by use or wont have become firmly fixed in the mind of the artist, do, in fact, constitute art and the artistic faculty; art, indeed, is the reason of the work in the mind of the artist. On the same terms, therefore, as art is attained to, is all knowledge and science acquired; for as art is a habit with reference to things to be done, so is science a habit in respect of things to be known: as that proceeds from the imitation of types or forms, so this proceeds from the knowledge of natural things. Each has its origin in sense and experience, and it is impossible that there can rightly be either art or science without visible instance or example. In both, that which we perceive in sensible objects differs from the image itself which we retain in our imagination or memory. That is the type, idea, forma informans; this is the imitation, the Eidos, the abstract species. That is a thing natural, a real entity; this a representation or similitude, and a thing of the reason. That is occupied with the individual thing, and itself is single and particular; this is a certain universal and common thing. That in the artist and man of science is a sensible thing, clearer, more perfect; this a matter of reason and more obscure: for things perceived by sense are more assured and manifest than matters inferred by reason, inasmuch as the latter proceed from and are illustrated by the former. Finally, sensible things are of themselves and antecedent; things of intellect, however, are consequent, and arise from the former, and, indeed, we can in no way attain to them without the help of the others. And hence it is, that without the due admonition of the senses, without frequent observation and reiterated experiment, our mind goes astray after phantoms and appearances. Diligent observation is therefore requisite in every science, and the senses are frequently to be appealed to. We are, I say, to strive after personal experience, not to rely on the experience of others; without which, indeed, no one can properly become a student of any branch of natural science, nor show himself a competent judge of what I am about to say on the subject of generation; for without experience and skill in anatomy, he would not better understand me than could one born blind appreciate the nature and difference of colours, or one deaf from birth judge of sounds. I would, therefore, have you, gentle reader, to take nothing on trust from me concerning the generation of animals; I appeal to your own eyes as my witnesses and judge. For as all true science rests upon those principles which have their origin in the operation of the senses, particular care is to be taken that by repeated dissection the grounds of our present subject be fully established. If we do otherwise, we shall but come to empty and unstable opinions; solid and true science will escape us altogether: just as commonly happens to those who form their notions of distant countries and cities, or who pretend to get a knowledge of the parts of the human body, from drawings and engravings, which but too frequently present things under false and erroneous points of view. And so it is, that in the present age we have an abundance of writers and pretenders to knowledge, but very few who are really learned and philosophers.
Thus much have I thought good, gentle reader, to present to you, by way of preface, that understanding the nature of the assistance to which I have trusted, and the counsel by which I have been led in publishing these my observations and experiments; and that you yourself in passing over the same ground, may not merely be in a condition to judge between Aristotle and Galen, but, quitting subtleties and fanciful conjectures, embracing nature with your own eyes, that you may discover many things unknown to others, and of great importance.
Of the same matters, according to Aristotle.
There is no such thing as innate knowledge, according to Aristotle; neither opinion, nor art, nor understanding, nor speech, nor reason itself, inhere in us by nature and from our birth; but all of these, as well as the qualities and habitudes, which are believed to be spontaneous, and to lie under the control of our will, are to be regarded as among the number of those things that reach us from without according to nature: such as the virtues and the vices, for which men are either praised and rewarded or reproved and punished. All our knowledge, therefore, of every kind has to be acquired. But this is not the place to inquire into the first principles of knowledge.
I believe, however, that it will not be useless if I premise a few words as to whence and how our knowledge reaches us, both with a view to rendering what I shall say on the subject of generation more readily intelligible, and of removing any doubts that may arise out of this opinion of the Stagirite,[125] who asserts that all doctrine and discipline based on reason are derived from antecedent knowledge; whence it seems to follow that there is either no first knowledge, or that this must be innate, a conclusion which is in contradiction with what has already been stated.
The doubt, however, is by and by resolved by Aristotle[126] himself, when he treats of the mode in which knowledge is acquired: for after he has taught that all certain knowledge is obtained through syllogism and demonstration, and made it manifest that every demonstrative syllogism proceeds from true and necessary first principles; he goes on to inquire how principles become known, and what the faculty is that knows; at the same time, too, he discusses the question, Whether habits, if not innate, are engendered; and whether, being innate, they lie concealed? “We have not,” he says, “these habits; for it happens that they are concealed from those who acquire the most admirable kinds of knowledge through demonstration. If, however, we receive them, not having had them previously, how should we become informed, how learn from non-antecedent knowledge? It is obvious, therefore, that they are neither possessed, nor can they be engendered in the ignorant and those who are endowed with no habit. Whence it is essential that some faculty be possessed, not however any which were more excellent, more exquisite than they. Now it seems a thing common to all animals, that they have a congenital power of judging, which we call sense. Since sense is innate, then, the things perceived by sense remain in some animals; in others they do not remain. Those in whom they do not remain, however, have either no knowledge at all, or at least none beyond the simple perception of the things which do not remain; others, again, when they perceive, retain a certain something in their soul. Now, as there are many animals of this description, there is already a distinction between one animal and another; and to this extent, that in some there is reason from the memory of things; and in others there is none. Memory, therefore, as is said, follows from sense; but from repeated recollection of the same thing springs experience (for repeated acts of memory constitute a single experience). From experience, however, or from the whole and universal stored quietly in the mind, (one, to wit, in place of a multitude--because in the whole crowd of particulars there is one and the same universal,) is derived the principle of art and of science: of art, if it belong to production (i. e. action); of science, if it belong to that which is (i. e. the knowledge of entity). Consequently there are neither any definite habits that are innate, nor any habits that are formed from other and more known habits, but from sense.”
From which words of Aristotle it plainly appears by what order or method any art or science is acquired, viz. The thing perceived by sense remains; from the permanence of the thing perceived results memory; from multiplied memory, experience; from experience, universal reason, definitions, and maxims or common axioms, the most certain principles of knowledge; for example, the same thing under like conditions cannot be and not be; every affirmation or negation is either true or false; and so on.
Wherefore, as we have said above, there is no perfect knowledge which can be entitled ours, that is innate; none but what has been obtained from experience, or derived in some way from our senses; all knowledge, at all events, is examined by these, approved by them, and finally presents itself to us firmly grounded upon some pre-existing knowledge which we possessed: because without memory there is no experience, which is nothing else than reiterated memory; in like manner memory cannot exist without endurance of the things perceived, and the thing perceived cannot remain where it has never been.
The supreme dictator in philosophy again and elsewhere expresses himself very elegantly in the same direction:[127] “All men desire by nature to know; the evidence of this is the pleasure they take in using their senses, among which the sight is that which is particularly preferred, because this especially serves us to acquire knowledge, and informs us of the greatest number of differences. Nature, therefore, endowed animals with sense; some of them, however, have no memory from the operations of their senses; others, again, have memory; and this is the reason wherefore some are more intelligent, and some more capable of receiving instruction than others, those, namely, that want recollection. Some show discretion independently of tuition: inasmuch as there are many that do not hear, such as bees and others of the same kind. But all animals which along with memory have the faculty of hearing are susceptible of education. Other creatures, again, live possessed of fancy and memory, but they have little store of experience; the human kind, however, have both art and reasoning. Now experience comes to man through memory; for many memories of the same thing have the force of a single experience: so that experience appears to be almost identical with certain kinds of art and science;[128] and, indeed, men acquire both art and science by experience: for experience, as Polus rightly remarks, begets art, inexperience is waited on by accident.”
By this he plainly tells us that no one can truly be entitled discreet or well-informed, who does not of his own experience, i. e. from repeated memory, frequent perception by sense, and diligent observation, know that a thing is so in fact. Without these, indeed, we only imagine or believe, and such knowledge is rather to be accounted as belonging to others than to us. The method of investigating truth commonly pursued at this time therefore is to be held as erroneous and almost foolish, in which so many inquire what others have said, and omit to ask whether the things themselves be actually so or not; and single universal conclusions being deduced from several premises, and analogies being thence shaped out, we have frequently mere verisimilitudes handed down to us instead of positive truths. Whence it comes that pretenders to knowledge and sophists, trimming up the discoveries of others, changing the arrangement only, or the language, and adding a few things of no importance, audaciously send them forth as their own, and so render philosophy, which ought to be certain and perspicuous, obscure and intricate. For he who reads the words of an author and fails, through his own senses, to obtain images of the things that are conveyed in these words, derives not true ideas, but false fancies and empty visions; whence he conjures up shadows and chimeras, and his whole theory or contemplation, which, however, he regards as knowledge, is nothing more than a waking dream, or such a delirium as the sick fancy engenders.
I therefore whisper in your ear, friendly reader, and recommend you to weigh carefully in the balance of exact experience all that I shall deliver in these Exercises on the Generation of Animals; I would not that you gave credit to aught they contain save in so far as you find it confirmed and borne out by the unquestionable testimony of your own senses.
The same course is even advised by Aristotle, who, after having gone over a great many particulars about bees, says at length:[129] “That the generation of bees takes place in this way appears both from reason and from those things that are seen to occur in their kind. Still all the incidents have not yet been sufficiently examined. And when the investigation shall be complete, then will sense be rather to be trusted than reason; reason, however, will also deserve credit, if the things demonstrated accord with the things that are perceived by sense.”
Of the Method to be pursued in studying Generation.
Since in Animal Generation, (and, indeed, in all other subjects upon which information is desired,) inquiry must be begun from the causes, especially the material and efficient ones, it appears advisable to me to look back from the perfect animal, and to inquire by what process it has arisen and grown to maturity, to retrace our steps, as it were, from the goal to the starting place; so that when at last we can retreat no further, we shall feel assured that we have attained to the principles; at the same time we shall perceive from what primary matter, and from what efficient principle, and in what way from these the plastic force proceeds; as also what processes nature brings into play in the work. For primary and more remote matter, by abstraction and negation (being stripped of its garments as it were) becomes more conspicuous; and whatever is first formed or exists primarily in generation, is the material cause of everything that succeeds. For example, before a man attains to maturity, he was a boy, an infant, an embryo. And then it is indispensable to inquire further as to what he was in his mother’s womb before he was an embryo or fœtus; whether made up of three bubbles, or a shapeless mass, or a conception or coagulum proceeding from the mingled seminal fluids of his parents, or what else, as we have it delivered to us by writers. In like manner, before a fowl had attained to maturity or perfection,--because capable of engendering its like,--it was a chicken; previous to which it was an embryo or fœtus in the egg; and before this, Hieronymus Fabricius, of Aquapendente, has observed rudiments of the head, eyes, and spine. But when he asserts that the bones are formed before the muscles, heart, liver, lungs, and precordial parts, and contends that all the internal organs must exist before the external ones, he follows probabilities according to previous notions rather than inspection; and quitting the evidences of sense that rest on anatomy, he seeks refuge in reasonings upon mechanical principles; a procedure that is anything but becoming in a great anatomist, whose duty it was faithfully to narrate the changes he observed taking place day by day in the egg, up to the period when the fœtus is perfected; and this the rather as he expressly proposed to himself to write the history of the formation of the chick in the egg, and to exhibit in figures what happens in the course of each successive day. It would have been in harmony with such a design, I say, had we been informed, on the testimony of the senses, of what parts are formed first, together, or subsequently in the egg; and not had mere opinions or musty conjectures, and the instances of houses and ships, adduced in illustration of the order and mode of formation of the parts.
We, therefore, in conformity with the method proposed, shall show in the first place in the egg, and then in the conceptions of other animals, what parts are first, and what are subsequently formed by the great God of Nature with inimitable providence and intelligence, and most admirable order. Next we shall inquire into the primary matter out of which, and the efficient cause by which generation is accomplished, and also the order and economy of generation, as observed by us; that from thence, from its own work, we may have some certain information of the several faculties of the formative and vegetative soul, and of the nature of the soul itself, judging from its members or organs, and their functions.
This, indeed, cannot be done in all animals: first, because a sufficient number of several of these cannot be commanded; and again, because, from the small size of many, they escape our powers of vision. It must suffice, therefore, that this is done in some kinds which are more familiarly known to us, and that we refer all the rest to these as types or standards.
We have, therefore, selected those that may tend to render our experiments more undeniable, viz. the larger and more perfect animals, and that are easily within reach. For in the larger animals all things are more conspicuous; in the more perfect, they are also more distinct; and in those that we can command, and that live with us, everything is more readily examined: we have it in our power so often as we please to repeat our observations, and so to free them from all uncertainty and doubt. Now, among oviparous animals of this description, we have the common fowl, the goose, duck, pigeon; and then we have frogs, and serpents, and fishes; crustacea, testacea, and mollusca; among insects, bees, wasps, butterflies, and silkworms; among viviparous creatures, we have sheep, goats, dogs, cats, deer, and oxen; lastly, we have the most perfect of all animals, man.
Having studied and made ourselves familiar with these, we may turn to the consideration of the more abstruse nature of the vegetative soul, and feel ourselves in a condition to understand the method, order, and causes of generation in animals generally; for all animals resemble one or other of those above mentioned, and agree with them either generally or specifically, and are procreated in the same manner, or the mode of their generation at least is referrible by analogy to that of one or other of them. For Nature, perfect and divine, is ever in the same things harmonious with herself, and as her works either agree or differ, (viz. in genus, species, or some other proportion,) so is her agency in these (viz. generation or development) either the same or diverse. He who enters on this new and untrodden path, and out of the vast realm of Nature endeavours to find the truth by means of anatomical dissections and experiments, is met by such a multitude of facts, and these of so unusual an aspect, that he may find it more difficult to explain and describe to others the things he has seen, than he reckoned it labour to make his observations; so many things are encountered that require naming; such is the abundance of matter and the dearth of words. But if he would have recourse to metaphors, and by means of old and familiar terms would make known his ideas concerning the things he has newly discovered, the reader would have little chance of understanding him better than if they were riddles that were propounded; and of the thing itself, which he had never seen, he could have no conception. But then, to have recourse to new and unusual terms were less to bring a torch to lighten, than to darken things still more with a cloud: it were to attempt an explanation of a matter unknown by one still more unknown, and to impose a greater toil on the reader to understand the meaning of words than to comprehend the things themselves. And so it happens that Aristotle is believed by the inexperienced to be obscure in many places; and on this account, perhaps, Fabricius of Aquapendente rather intended to exhibit the chick in ovo in his figures than to explain its formation in words.
Wherefore, courteous reader, be not displeased with me, if, in illustrating the history of the egg, and in my account of the generation of the chick, I follow a new plan, and occasionally have recourse to unusual language. Think me not eager for vainglorious fame rather than anxious to lay before you observations that are true, and that are derived immediately from the nature of things. That you may not do me this injustice, I would have you know that I tread in the footsteps of those who have already thrown a light upon this subject, and that, wherever I can, I make use of their words. And foremost of all among the ancients I follow Aristotle; among the moderns, Fabricius of Aquapendente; the former as my leader, the latter as my informant of the way. For even as they who discover new lands, and first set foot on foreign shores, are wont to give them new names which mostly descend to posterity, so also do the discoverers of things and the earliest writers with perfect propriety give names to their discoveries. And now I seem to hear Galen admonishing us, that we should but agree about the things, and not dispute greatly about the words.
ON
ANIMAL GENERATION.