1 Fortnnio Liceti, 1577-1057, a celebrated Italian physician and scholar, who taught logic at Pisa, 1600-l(i09; philosophy at Padua till 1(531; then philosophy at Bologna; and finally, theoretic medicine at Padua from 1(545 till his death. He was a great admirer of Aristotle, and wished to admit nothing beyond his doctrines, and thus contributed to render both philosophy and medicine sta tionary. For the matter to which Leibnitz here refers, cf. Licetus, De spontaneo riventium ortu, lib. quat., fol., Vicentire, 1(518, Bk. I., chap. 28, pp. 34-.%, Sexta confirmatio spontanei ortus hominnm petita ex humanis figuris in belluis, ac lapidibus enodatur aperiendo taliuin figurarum caussas, in which chapter Licetus treats of various monsters, referring to his De monstrornm mentioned below, and to his father's, Giuseppe Liceti, an Italian physician, died 1599, Diahr/us de genitalium usu et diynitate, or II C'eva, dell' ouvero eccellenza ed uso de' r/enitali, 1598, De monstrorum caussis, natura, et differentiis lib. duo, 2d ed., 4to, Petavii, 1(!34, pp. 13, 183, 194: " De monstrorum humanorum reale existential"; the same, with additions by Gerard Blasius, 4to, Amstelodami, 1(5(55, pp. 13, 183, 194; the same, in the French trans., Truite dcs monstres, by Jean Palfyn, 1(550-1730, in his Description anutomique des parties de lafemme qui servent a la generation, etc., 4to, Leyden, 1708, pp. 13, 197, 208. — TR.
352 LEIBNITZ'S CRITIQUE OF LOCKE [BK. m Th. I admit it, and if that occurred and if any one had done, as a certain writer, a monk of the olden time, named Hans Kalb (Jean le veau — John the calf) who l painted himself with a calf's head, the pen in his hand, in a book he had written, which procedure caused some foolishly to think that this writer had in reality a calf's head, — if, I say, that hap pened, we should be more cautious hereafter in getting rid of monsters. For there is some probability that reason would maintain it with theologians and with jurisconsults in spite of the figure and even in spite of the differences which the anatomy would furnish to the physicians, which would as little injure the quality of man as the reversal of the viscera in that man whose anatomy some persons of my acquaintance have seen at Paris, which has made some stir, in which nature " Peu sage et sans doutc en d&bauche Pla^a le foye au costs gauche Et de meme vice versa Le cceur a la droite pla<ja," i.e. " unwise and doubtless in debauch placed the liver upon the left side and likewise vice versa the heart upon the right," if I rightly remember some of the verses which the late Mr. Alliot2 the father (a famous physician because he passed as skilful in the treatment of cancers) showed me of his own making upon this prodigy. It is a matter of course, provided the variety of conformation does not go too far in the case of rational animals and that no return is made to the times when animals spoke, for then we should lose our especially peculiar advantage of reason 3 and should henceforth be more attentive to birth and the external in order to be able to dis- 1 Errlmann and Jacques add " qui " after " le veau." — TR.
2 Pierre Alliot, a French physician of the seventeenth century, born at Bar-le-Duc, reputed to have great skill in the treatment of cancer and other malignant ulcers. His most distinguished patient was Anne of Austria, the mother of Louis XIV., whom he treated unsuccessfully in Paris in 1665. Not withstanding his failure, he was appointed physician to the king. His published works include Theses medicse de motu sannuinis circulate ct de morbis ex sere, Pont-a-Mousson, 16G3, 8vo; Epistola de cancro apparente, and Nuntius profli- gati sine ferro et iyne carcinomatis, both Bar-le-Duc, 1664, 12mo. His son, Jean Baptiste Alliot, was physician to Louis XIV., and published Traite du cancer oil I'on erpliqne sa nature et ou Von propose les moycns les plus surs pour le (fuerir methodiquement, Paris, 1698, 12mo. — TR.
3 The French text is: " nostre privilege de la raisoii en preciput," etc. — TR.
en. vi] ON HUMAN UNDERSTANDING 353 cern those of Adam's race from those who may descend from a king or patriarch of some canton of apes in Africa; and our learned author was right in his remark (§ 29) that if Balaam's ass had all her life discoursed as rationally as she did once with her master (supposing it was a prophetic vision), she would always have had difficulty in obtaining rank and a seat among women.
Ph. You laugh, I see, and perhaps the author laughed also; but, to speak seriously, you see that you cannot always assign fixed limits to species.
Tk. I have already agreed to this; for when the question concerns fictions and the possibility of things, the passage from species to species may be insensible, and to discern them would sometimes be about as impossible as to decide how much hair a man must be allowed that he may not be bald. This indeterminateness would be true even when we knew perfectly the internal nature of the creatures under discussion. But I do not see that it can prevent things from having real essences independent of the understanding, and us from know ing them. It is true that the names and limits of species would sometimes be like the names of measures and weights, where choice is necessary in order to have fixed limits. But ordinarily there is nothing of the kind to fear, species too much alike seldom occurring together.
§ 28. Ph. It seems we agree here at bottom, although we differ somewhat in terms. I also admit that there is less arbitrariness in the denomination of substances than in the names of the mixed modes. For few venture to unite the bleating of a sheep with the figure of a horse, or the color of lead with the weight and fixedness of gold, and we prefer to draw copies after nature.1 Tli. This is not so much because in substances regard is had only to that which exists effectively, as because there is no certainty in the case of physical ideas (which are not very thoroughly understood) that their union is possible and useful, if there is no actual existence to guarantee it. But this also takes place in the modes, not only when their obscurity is impenetrable by us, as sometimes happens in physics, but also 1 That is, to follow experience in the formation of our ideas, aud to conform our iuner world in general to that furnished by nature. — TR.
354 LEIBNITZ'S CRITIQUE OF LOCKE [BK. in when it is difficult of penetration, enough examples of which occur in geometry. For in both of these sciences it is not within our power to make combinations according to our fancy, otherwise we should be right in speaking of regular decahedrons, and should seek in the semicircle1 a centre of magnitude, as there is in it a centre of gravity. For it is in fact surprising that the first is there, and that the second cannot be. Now while in the modes the combinations are not always arbitrary, we find on the other hand that in substances they sometimes are so; and it often depends on ourselves to make combina tions of qualities in order further to define substantial beings in advance of experience, when we understand enough of these qualities to judge of the possibility of the combination. Thus it is that expert gardeners in the orangery can rationally and successfully propose to produce some new species and give it a name in advance.
§ 29. Ph. You will always agree with me that when the question arises of defining species, the number of ideas com bined depends upon the different application, industry, or fancy of the one forming this combination, as it is the figure which regulates most frequently the determination of the species of vegetables or animals, and likewise as regards the majority of natural bodies which are not produced by seeds, it is the color which is most strongly adhered to. § 30. In truth these are often only confused conceptions, gross and inexact, and it is very essential that men agree as to the precise number of simple ideas or qualities which belong to a given species or a given name, for pains, skill, and time are needed to find simple ideas which are constantly united. However a few of the qualities composing these inexact definitions are ordinarily sufficient in conversation; but in spite of the stir about gen era and species, the forms, of which so much has been said in the schools, are only chimeras which avail us nothing in fur nishing an entrance into the knowledge of specific natures.
Th. Whoever makes a possible combination, is not at all mistaken therein, nor in giving it a name; but he is mistaken 1 Such combinations of essentially self-contradictory ideas may easily be united in a complex term, and be apparently clear and possible, until analyzed and compared with reality, when their confusion and impossibility is at once made evident. — TR.
CH. vi] ON HUMAN UNDERSTANDING 355 if he thinks that his conception is altogether that which others more expert have conceived under the same name or in the same body. He perhaps conceives a genus too common instead of another more specific. There is nothing in all this contrary to the schools, and I do not see why you return here to the charge against genera, species, and forms, since it is necessary for you to recognize indeed the genera, species, and even the internal essences or forms, which AVC do not pretend to employ in order to know the specific nature of the thing, although we admit we are still ignorant of them.
§ 30. Ph. It is at least evident that the limits we assign to species are not exactly conformed to those established by nature. For in our need of general names for present use, we do not put ourselves to the trouble of discovering the qualities which would give us superior knowledge of their most essential dif ferences and agreements, but we ourselves distinguish them into species in virtue of certain appearances which are mani fest to everybody, that we may more easily communicate with others.
Th. If we combine compatible ideas, the limits we assign to species are always exactly conformed to nature; and if we are careful to combine ideas actually found together, our notions are also conformed to experience; and if we consider them as provisional only for actual bodies, without excluding ex periment made or to be made for further discovery therein, and if we have recourse to experts, when a definite question arises with reference to what is openly understood by the name, we shall not err in the matter. Thus nature may furnish ideas the most perfect and most convenient, but she will not give the lie to those we have which are good and natural, although not perhaps the best and most natural.
§ 32. Ph. Our generic ideas of substances, as that of metal, for example, do not follow exactly the models set them by nature, since you cannot find any body including simply malle ability and fusibility without other qualities.
Th. No one asks for such models and it would not be reason able to ask for them; furthermore they do not occur in the most distinct notions. AVe never find a number in which there is nothing to notice but multitude in general, an extension in which there is only extension, a body in which there is only 356 LEIBNITZ'S CRITIQUE OF LOCKE [BK. in solidity, and no other qualities; and when the specific differ ences are positive and contrary it is very essential that the genns share in them.
Ph. If, then, any one thinks that a man, a horse, an animal, a plant, etc., are distinguished by real essences made by nature, he must think that nature is very liberal ivith these real essences, if she produces one of them for the body, another for the animal, and still another for the horse, and that she bestows freely all these essences upon Bucephalus; whilst genera and species are only signs more or less comprehensive.
Th. If you take real essences as these substantial models, which exist as a body and nothing more, an animal and nothing more specific, a horse without individual qualities, you are right in treating them as chimeras. And no one has main tained, I think, not even the greatest Realists of former times, that there are as many substances confining themselves to the generic as there are genera. But it does not follow that if general essences are not this, they are merely signs; for I have many times remarked to you that there are possibilities in the resemblances. In like manner from the fact that colors are not always substances or extracted dyes, it does not follow that they are imaginary. For the rest you cannot think nature too liberal; she is so beyond all that we can invent, and all advan tageous compatible possibilities are found realized upon the grand theatre of her representations. There were formerly two axioms among philosophers: that of the Realists seemed to make nature prodigal, and that of the Nominalists seemed to declare her stingy. The one says that nature suffers no vacuum, and the other that she does nothing in vain. These two axioms are good provided you understand them; for nature is like a good economist, who saves where it is necessary in order to be grand at times and places. She is grand in effects, and sparing in the causes she employs.
§ 34. Ph. Without amusing ourselves longer with this dis cussion upon real essences, it is enough that we obtain the pur pose of language and the usage of words which is to indicate our thoughts in an abridged form. If I wish to speak to any one of a species of birds three or four feet in height, whose skin is covered with something between feathers and hair, of a dark brown color, without wings, but in their place two or CH. vi] ON HUMAN UNDERSTANDING 357 three small branches, like those of the broom, which descend to the lower part of the body, with long and large legs, the feet armed only with three claws and without a tail; I am. compelled to make this description whereby I can make myself understood by others. But when I am told that the name of this animal is Cassowary, I can then use this name to designate in discourse this entire complex idea.
Tli. Perhaps a very exact idea of the covering of the skin or of some other part would suffice by itself alone to distin guish this animal from every other known, as Hercules was known by his gait, and as the lion was recognized by his claw according to the Latin proverb. But the more circumstances you heap up, the less provisional is your definition.
§ 35. Ph. We may curtail the idea in this case without prejudice to the thing; but when nature curtails it, it is a question whether the species remains. For example: if a body existed having all the qualities of gold except mallea bility, would it be gold? it depends upon men to decide. They are then the ones who determine the species of things.
Th. Not at all; they would determine only the name. But this experience would teach us that malleability has no neces sary connection with the other qualities of gold taken together. It would teach us then a new possibility and consequently a new species. As for gold which is eager l or brittle, this comes only from additions, and is not consistent with the other tests of gold; for the cupel and antimony remove this eagerness from it.
§ 36. Ph. A portion of our doctrine follows that will appear very strange. Each abstract idea having a certain name forms a distinct species. But what of that, if nature so wills it? I should be glad to know why a lap-dog and a greyhound are not as distinct species as a spaniel and an elephant.
Th. I have distinguished above the different senses of the word species. Taking it logically, or mathematically rather, the least dissimilitude may suffice. Thus each different idea will give another species, and it makes no difference whether it has a name or not. But, physically speaking, we do not at tend to all the varieties, and we speak either distinctly when the question concerns only appearances, or conjecturally when the i Cf. Locke, Philos. Works, Vol. 2, p. 05 (Bolm's ed.). — Tn.
358 LEIBNITZ'S CRITIQUE OF LOCKE [UK. in question concerns the inner truth of things, presuming therein some essential and immutable nature, like reason in man. We presume then, that whatever differs only by accidental changes, like water and ice, quicksilver in the liquid form and as sublimate, is of the same species: and in organic bodies the provisional mark of the same species is usually placed in the generation or race, as in those most alike it is placed in repro duction. It is true we cannot judge with precision, for lack of knowledge of the inner nature of things; but, as I have said more than once, we judge provisionally and often con- jecturally. But when we wish to speak only from the external, for fear of saying nothing certain, there is some latitude; and to dispute then whether a difference is specific or not is to dispute about the name; and in this sense there is so great a difference between dogs, that we may very well say that the house-dogs of England and the dogs of Boulogne belong to different species. It is not impossible, however, that they belong to a remote identical or similar race, which we should find if we could go back very far, and that their ancestors were alike or identical, but that after great changes, some of the posterity have become very large and others very small.
We may indeed believe also without offending reason that they have in common an inner nature, constant, specific, which is no longer subdivided thus, or which is not found here in several other such natures, and consequently is no longer varied save by accidents; although there is also nothing to make us judge that this must necessarily be so in all that which we call the lowest species (species inftma). But there is no likeli hood that a spaniel and an elephant are of the same race, and that they have such a specific common nature. Thus in the different sorts of dogs, speaking of appearances, we may dis tinguish species, and speaking of the inner essence we may be in suspense: but comparing the dog and the elephant there is no reason for attributing to them externally or internally that which would make us think them of one and the same species. So there is in this case no occasion for suspense in the face of the presumption. In man we can also distinguish species logically speaking, and if we stopped with the external we should find also, speaking physically, differences which could pass as specific. Thus a traveller was found who thought CH. vi] ON HUMAN UNDERSTANDING 359 that the Negroes, Chinese, and finally the Americans were not of one and the same race among themselves nor with the peoples resembling us. But as we know the essential inner nature of man, i.e. the reason, which dwells in the man him self and is found in all men, and as we notice nothing fixed and internal among us which forms a subdivision, we have no reason to judge that there is in men, according to the truth of the inner nature, an essential specific difference, while such difference is found between man and beast, supposing that the beasts are only empirical, according as I have explained above, as in fact experience gives us no reason for forming any other judgment.
§ 39. Ph. Let us take the example of an artificial thing whose internal structure is known to us. A time-piece that only indicates the hours, and one that strikes, are of one species only for those who have only one name by which to designate them; but for him who designates the first by the name match, and second clock, they are in relation to him dif ferent species. It is the name and not the inner disposition which makes a new species, otherwise there would be too many species. There are watches with four wheels, and others with five; some have strings and fusees,1 and some not; some have a free balance, and others are regulated by a spiral spring and others by hog's bristles. Does any one of these things suffice to make a specific difference? 1 say no, so long as these time-pieces agree in name.
Tli. And I for my part say yes, for without stopping at names, I should consider the varieties of contrivance and especially the differences of the balance; for since a spring has been applied which governs the vibrations according to its own and consequently renders them more equal, pocket- watches have changed their character, and have become in comparably more accurate. I have indeed mentioned before another principle of equality which might be applied to watches.
Ph. If any one wishes to make divisions based upon the differences which he knows in the internal configuration he may do so; but they would not be distinct species with rela tion to the people who are ignorant of this construction.
1 Locke has "physics," Philos. Works, Vol. 2, p. 07 (Bohn's ed.). — TR.
300 LEIBNITZ'S CRITIQUE OF LOCKE [UK. in TIi. I do not know why those with you always wish to make virtues, truths, and species depend upon our opinion or knowledge. They exist in nature, whether we know it and approve or not. To speak otherwise is to change the names of things and received language without any reason. Men up to the present time have believed that there are many kinds of clocks or watches, without informing themselves in what they consist or how they may name them.
Ph. You have however recognized not long since that when men wish to distinguish physical species by appearances, they limit them in an arbitrary way, where they find it to the pur pose, i.e. according as they find the difference more or less considerable and according to the end they have. And you yourself have made use of the comparison of weights and measures, which are regulated and given their names accord ing to the good pleasure of man.
Th. It is since then that I have begun to understand you. Between specific differences purely logical, for which the least variation of assignable definition suffices, however accidental it be, and between specific differences purely physical, based upon the essential or immutable, we may place a mean, which cannot be precisely determined; it is regulated by the most important appearances, which are not altogether immutable, but which do not change easily, the one approaching the essential more than the other. And as a connoisseur too may go farther than another, the thing appears arbitrary and has some relation to men, and it appears convenient to regulate names also according to these principal differences. "We can then speak thus, that there are specific civil differences and nominal species which must not be confounded with what I have called above nominal definitions, and which have place in differences specifically logical as well as physical. For the rest, besides common usage, the laws themselves may give authority to the significations of words, and then the species would become legal, as in the contracts which are called nominati, i.e., designated by a particular name. For example as the Roman Law made the age of puberty commence at the end of the fourteenth year. This entire consideration is not to be despised, but I do not see that it is of very much use here, for besides the fact that you have appeared to me to en. vi] ON HUMAN UNDERSTANDING 3G1 apply it sometimes where it did not apply, we shall accom plish nearly the same result if we consider that it rests with men to proceed in subdivisions as far as they find them to the purpose, and to abstract ulterior differences without the necessity of denying them; and that it also rests with them to choose the certain, notwithstanding the uncertain, in order to fix some notions and measures by giving them names.
Ph. I am much pleased that we are here no longer so far apart as we appeared. § 41. You agree then, sir, I see, that artificial as well as natural things are species contrary to the view of some philosophers. § 42. But before leaving the names of substances, I would add that of all the diverse ideas we have, they alone are ideas of substances which have proper or individual names; for it rarely happens that men need to make frequent mention of any individual quality or other individual accident. Besides individual acts perish at once and the combination of circumstances which thereby comes about only subsists as in the substances.
Th. There are, however, cases where it has been necessary to remember an individual accident and to give it a name; thus your rule is ordinarily good, but there are exceptions to it. Keligion furnishes us with them; for example we cele brate each year the memory of the birth of Jesus Christ. The Greeks call this event Theogeny, and that of the adoration of the Magi, Epiphany. And the Hebrews call the Passah par excellence the passage of the angel who caused the death of the eldest sons of the Egyptians without touching those of the Hebrews; and this is why they were to celebrate its memory every year. As for the species of artificial things, the scholastic philosophers found difficulty in admitting them into their pre dicaments; but there was little necessity for their hesitation since these predicamental tables were destined for use in mak ing a general review of our ideas. It is Avell however to rec ognize the difference existing between perfect substances and between the assemblages of substances (aggregata) which are substantial entities composed either by nature or by the art of man. For nature has also such aggregates, as the bodies whose mixture is imperfect (imperfects mixta) to use the language of our philosophers, which constitute no unum per se and do not possess in themselves a perfect unity. I believe however that 302 LEIBNITZ'S CRITIQUE OF LOCKE [»K. in