degrees, and by a continued series of things, which in each remove differ very little one from the other. There are fishes that have wings, and to whom, the air is not strange, and there are birds inhabiting the water whose blood is cold like that of the fishes, and whose flesh so strongly resembles theirs in taste that the scrupulous are allowed to eat them on fish- days. There are animals so closely approaching the species of birds and of beasts that they hold the middle ground between them. The amphibia contain both terrestrial and aquatic ani mals. Seals live upon the land and in the sea; and porpoises (whose name signifies sea-hog) have the warm blood and the entrails of a hog. Xot to speak of that which is reported of sea-men,1 there are some animals who seem to have as much knowledge and reason as some that are called men; and there is so close a relation between animals and vegetables, that if you take the most imperfect of the one and the most perfect of the other, you will scarcely perceive any considerable dif ference between them. Thus, until we reach the lowest and least organized parts of matter, we shall find everywhere species bound together, and differing only by degrees almost impercept ible. And when we consider the wisdom and infinite power of the Author of all things, we have reason to think that it is con formed to the magnificent harmony of the universe and to the great design as well as to the infinite goodness of this sovereign architect, that the different species of creatures ascend, also, little by little from us towards his infinite perfection. Thus we have reason to be persuaded that there are many more species of creatures above us than below us, because we are much more distant in degrees of perfection from the infinite being of God than from that which approaches nearest to nothing. Yet we have no clear and distinct idea of all these different species.
Th. [I had intended in another place to say something not unlike what you, sir, have just set forth; but I am glad to have been anticipated when I see that you state things better than I could hope to have done. Clever philosophers 2 have 1 I.e. mermaids; so Looke, "mermaids or sea-men," Philos. Works, Vol. 2, 334 LEIBNITZ'S CRITIQUE OF LOCKE [J?K. in discussed this question: utrum detur vacuum formarum, I.e. whether there are possible species, which, however, do not exist, and which nature may seem to have forgotten. I have reason to believe that all possible species are not compossible in the universe, great as it is, and that, too, not only in rela tion to things which exist contemporaneously, but also in relation to the whole series of things. That is to say, I believe that there are of necessity species which have never existed and never will exist, not being compatible with this series of creatures which God has chosen. But I believe that all things, which the perfect harmony of the universe can receive, exist therein. That there may be intermediate creatures between those which are far apart is in conformity with this same harmony, although this is not always in one and the same globe or system, and that which is between two species is sometimes so in relation to certain circumstances and not in relation to others. Birds, so different from man in other things, approach him in speech; but if monkeys could speak like parrots, they would go farther. The law of continuity1 declares that nature leaves no gap in the order she follows; but every form or species is not the whole order. As for spirits or genii, as I hold that all created intelligences have organized bodies, whose perfection corresponds to that of the intelligence, or the mind, which is in this body in virtue of the pre-established harmony, I hold that in order to gain any conception of the perfections of spirits above us, it will be of great service to imagine these perfections also in bodily organs which surpass our own. It is a case in which the liveliest D. 2, 93: " II se peut cependant, que ce Chevalier ait encor eu quelque bon eu- thousiasme, qui 1'ait transporte dans ce monde invisible, et dans cette tftendue inftnie, dont il parle, et que je crois estre celle des idees ou des formes, dont out parle encor quelques Scholastiques en mettant en question, ittrum detur vacuum formarum." — TR.
1 Cf. New Essays, Preface, ante, p. 50, Bk. IV., chap. 16, § 12, Th., infra, p. 552; Thdodicte, III., § 348, Gerhardt, G, 321, Erdmann, 605, b, Jacques, 2, 270; Letter to Bayle, in the " Nouvelles de la Republique des Lettres," July, 1687, G. 3, 52, E. 104, trans. Duncan, Philos. Works of Leibnitz, 33; Letter to Arnauld, 1690, G. 2, 13(5, E. 107, b, J. 1, 444, trans. D. 38. Animadversiones in partem generalem Principioruni Cartesianorum, Ft. II., ad Art. 45, G. 4, 375, Duncan, 61; Guhrauer, G. W. Fretherr v. Leibniz, eine Biographie, 1, 264, and notes, pp. 31-33, a letter to an unknown person, Oct. 16, 1707, containing a very clear statement of the principle or law of continuity; translation, Appendix, pp. 712-714. — TR.
CH. vi] ON HUMAN UNDERSTANDING 335 and richest imagination, and, to avail myself of an Italian term which I cannot well express otherwise, the invenzione la piit, vaga, will be most timely in raising us above ourselves. And what I have said in justification of my system of harmony, which exalts the divine perfections beyond what we had dared to think, will assist us also in having ideas of creatures in comparably grander than we have had hitherto.
§ 14.1 Ph. To return for a little to the reality of species even in substances, I ask you if water and ice are different species?
TIi. [I, in my turn, ask you if gold melted in the crucible and gold cooled in bullion are of one and the same species?]
Ph. He does not reply to the question, who proposes an other, Qui litem lite resolvit.2 ]>ut you thereby admit that the reduction of things to species relates solely to the ideas we have of them, which suffice to distinguish them by names; but if we suppose that this dis tinction is founded upon their real and internal constitution, and that nature distinguishes existing things into so many species by their real essences, in the same manner as we ourselves distinguish them into species by these or those names, we shall Joe liable to great mistakes.
Tli. There is some ambiguity in the term species, or a being of a different species, which causes all this confusion; and when we have removed it, there will no longer be discussion save perhaps as regards the name. We may take species mathematically and physically. In mathematical strictness the least difference making two things in any respect dissimilar, makes them different in species. Thus, in geometry, all circles are of one and the same species, for they are all perfectly alike, and for the same reason all parabolas are also of the same species; but it is not the same with ellipses and hyperbolas, for of these there is an infinite number of sorts or species, as well as an infinite number of each species. All the numberless 1 Locke has § 13, Philos. Works, Vol. 2, p. 50. The numbering § 14 in the French text of all the editions is an error, as will be seen upon comparing the numbering of the next §, also 14, with Locke's text. Here also the texts coincide with Locke's. — TR.
336 LEIBNITZ'S CRITIQUE OF LOCKE [BK. m ellipses, in which the distance of the foci has the same ratio to the distance of the apices, are of one and the same species; but as the ratios of these distances vary only in size, it follows that all these infinite species of ellipses make only one genus, and that there are no subdivisions. On the other hand, an oval of three foci would have indeed an infinite number of such genera, and would have an infinitely infinite number of species, each genus having a number of them simply infinite. In this sense two physical individuals will never be perfectly similar, and what is more, the same individual will pass from species to species, for it is never wholly similar to itself even for more than a moment. But the men who establish physical species do not adhere to this strictness, and it depends upon them to say that a mass which they can make return to themselves under its first form continues to be one and the same species in their view. Thus we say that water, gold, quicksilver, common salt, continue the same, and are only disguised in ordinary changes; but in organized bodies, or in species of plants and of animals, we define species by generation, so that this similarity, which comes or may have come from one and the same origin or seed, would be of one and the same species.1 In man, besides human generation, we fasten upon the attribute rational animal; and, although there are men who live like beasts all their lives, we presume that it is not for want of faculty or principle, but that it is through impediments which stand in the way of this faculty. But it is not yet determined as regards all the external conditions which we wish to regard as sufficient to give this presumption. But whatever regulations men make for their denominations and for the rights attached to names, provided that their regulation is followed or made fast and intelligible, it will be founded in reality, and they will not be able to imagine species which nature, which includes even possibilities, has not produced or distinguished before them. As for the interior, although there is no external ap pearance which is not based upon the internal constitution, it is nevertheless true that one and the same appearance may sometimes result from two different constitutions. But in i Cf. New Essays, Bk. III., chap. 3, § 14, Th. (2), ante, p. 314; Dewey, Leib niz's New Essays, p. 215 sq. — TK.
CH. vi] ON HUMAN UNDERSTANDING 337 that case there will be something in common, and this is what we philosophers call the proximate formal cause. But although this should not be, as if according to Mariotte * the blue of the rainbow had an entirely different origin from the blue of the turquoise, unless there were a common formal cause (in which opinion I do not at all agree with him), and although we should agree that certain apparent natures which make us give names have nothing internal in common, our definitions would not cease to be grounded in real species; for the phenomena themselves are realities. We can say, then, that all which we truthfully distinguish or compare, nature dis tinguishes or makes agree also, although she has distinctions and comparisons which we do not know and which may per haps be better than ours. Thus much care and experience is yet necessary in order to assign genera and species in a manner sufficiently like nature. Modern botanists think that the dis tinctions taken from the forms of flowers most resemble the natural order.2 But they find therein, however, still much difficulty, and it would be advantageous to make comparisons and arrangements not only upon a single character, like that of which I have just spoken, which is taken from flowers, and is perhaps the most suitable up to this time for a possible system and convenient for learners, but also upon characters taken from other parts and relationships of plants: each basis of comparison deserving tables of its own; 3 without which we shall allow many subaltern genera, and many com parisons, distinctions, and useful observations to escape. But the more thoroughly we examine the generation of species, and the more we follow in the classifications the conditions which are there requisite, the closer we shall approach the natural order. Therefore, if the conjecture of some intelligent persons were found true, that there is in the plant besides the 2 Cf. Dutens, Leibnit. opera omnia, Vol. 2, Pt. II., p. 109 sq., Epistola G. G. Leibnitii ad A. C. Gackenholtzium, M. D. De Methodo Botanica, April 23, 3 Cf. Mor. Wilh. Drobisch, Neue Darstg. d. Loyik, 3d ed., Leipzig, 1803, p. 141 sq., where the so-called Collateral Distributions or Co-divisions, which Leibnitz here calls to mind, and " which are of especial importance in Statis tics," are discussed. Drobisch's work is considered " one of the most perfect presentations of the subject-matter from the poiiit of view of formal logic."
338 LEIBNITZ'S CRITIQUE OF LOCKE [UK. in seed (la gruine) or the recognized seed (la semence) correspond ing to the egg of the animal, another seed which would deserve the name masculine, i.e. a powder (pollen, visible very often, though sometimes, perhaps, invisible, as the seed (la graine) itself is in certain plants) which the wind or other ordinary accidents scatter in order to unite it with the seed which comes sometimes from one and the same plant, and sometimes, also (as in the hemp), from another neighboring plant of the same species, which plant consequently will be analogous to the male, though perhaps the female is never wholly destitute of this same pollen; if this conjecture, I say, were found true, and if the mode of generation of plants became better known, I do not doubt that the varieties which would be noticed would furnish a basis for very natural divisions. And if we had the penetration of some superior geniuses and knew enough about things, perhaps we should find therein fixed attributes for each species, common to all the individuals and always sub sisting in the same living organism, whatever alterations or transformations may happen to it, as in the best known of the physical species, the human, reason is such a fixed attribute, granted to each individual, and never to be lost, although it cannot always be perceived. But in default of this knowl edge we avail ourselves of the attributes which appear to us most convenient for distinguishing and comparing things, and in a word, for recognizing in them species or sorts; and these attributes have always their real grounds.]
§ 14. Ph. In order to distinguish substantial beings accord ing to the usual supposition, that there are certain essences or precise forms of things, whereby all existing individuals are naturally distinguished into species, it would be necessary to be assured, § 15. first, that nature always proposes, in the production of things, to make them participate in certain regular and established essences, as models; and, § 16. sec ondly, that nature always attains this end. But monsters give us reason to doubt both. § 17. It would be necessary to determine, in the third place, whether these monsters are really a distinct and new species, for we find that some of these monsters have few or none of those qualities which are supposed to result from the essence of that species whence they derive their origin, and to which they seem to belong in virtue of their birth.
CH. vi] ON HUMAN UNDERSTANDING 339 Th. When it is a question of determining whether monsters belong to a certain species, we are often reduced to conjecture. This shows us that we are not, then, limited to external con siderations, since we should divine whether the internal nature (as, for example, reason in man) common to the individuals of such a species, still suits (as birth makes us conjecture) these individuals, in whom a portion of the external characteristics, ordinarily found in this species, is lacking. But our incerti tude nowise affects the nature of things, and if there is such a common internal nature, it will or will not be found in the monster, whether we know it or not. And if the internal nature of any species is not found therein, the monster will be of its own species. But if there were no such internal nature in the species under discussion, and if the question was not decided by birth either, then the external marks alone would determine the species, and monsters would not belong to that species from which they deviate, unless taken in a manner a little vague and with some latitude; and in this case, also, our trouble in desiring to divine the species would be in vain. This is perhaps what you mean by all the objections you make to species taken as real internal essences. You ought then to prove, sir, that no common internal specific mark exists, since the external is wholly missing. But the contrary is found in the human species in which sometimes children who have some monstrosity reach an age in which they exhibit reason. Why, then, could there not be something similar in other species? It is true that for want of knowledge of them we cannot avail ourselves of it to define them, but the exterior takes its place, although we recognize the fact that it is insuffi cient for an exact definition, and that the nominal definitions themselves in these instances are only conjectural; and I have already stated above how sometimes they are only pro visional. For example, we might find a way to counterfeit gold so that it might satisfy all the tests which we have up to the present time; but we might also then discover a new method of testing which would give the means of distinguishing natural gold from this which is artificially made. The old journals at tribute both (discoveries) to Augustus, Elector of Saxony; x 1 Augustus I., the brother of Maurice, was Elector 1553-1580, and, according to Schaarschmidt, " shared with his wife, Auua of Denmark, the love for alchemy." — Tit.
340 LEIBNITZ'S CRITIQUE OF LOCKE [BK. in but I am not the man to guarantee this fact. But if it were true, we could have a more perfect definition of gold than we have at present, and if artificial gold could be made in quantity and cheap, as the alchemists claim, this neiv proof would be important; for by its means we could preserve for the human race the advantage which natural gold gives us in commerce by its rarity, while furnishing ourselves with a substance which is durable, uniform, easy to divide and to recognize, and precious in small volume. I wish to avail myself of this occasion to remove a difficulty (see § 50 of the chapter, " On the Names of Substances," in the author of the Essay on Understanding}. The objection is made that in saying: All gold is fixed, if we understand by the idea of gold the mass of certain qualities in which fixedness is comprised, we make only an identical and useless proposition, as if we said: Fixedness is fixedness; but if we understand thereby a substance given a certain internal essence, of which fixedness is a result, we shall not speak intelligibly, for this real essence is wholly unknown. I reply that the body given this internal constitution is designated by other external marks in which fixedness is not comprised, as if any one said: the heaviest of all bodies is also one of the most fixed. But all that is only provisional, for we might some day find a volatile body, as a new mercury, which would be heavier than gold, and upon which gold would float, as lead floats upon our mercury.
§ 19. Ph. It is true that in this way we can never know precisely the number of properties depending on the real essence of gold unless we know the essence of gold itself. § 21. [But if we limit ourselves precisely to certain properties, that Avill be sufficient to enable us to have exact nominal definitions which will serve us for the present, reserving to ourselves the privilege of changing the signification of names, if any new useful distinction is discovered.] But it is neces sary at least that this definition correspond to the use of the name, and be capable of being put in its place. This serves to refute those who maintain that extension constitutes the essence of body, for when it is said that one body gives an impulse to another, the absurdity would be manifest, if substi tuting extension (for body) we should say that one extension puts in motion another extension by means of an impulse, for on. vi] ON HUMAN UNDERSTANDING 341 in addition solidity is necessary. In like manner no one will say that reason, or that which makes man rational, makes conversation; for reason does not constitute the entire essence of man; there are rational animals who converse with each other.
Th. I think you are right: for the objects of abstract and incomplete ideas are not sufficient to give the subjects of all the actions of things. But I think that conversation agrees with all minds who can interchange their thoughts. The scholastics are greatly troubled regarding the angelic method of communication; but if they would accord the angels subtile bodies, as I do, following the ancients, they would experience no further difficulty in that regard.1 § 22. Ph. There are some creatures in the world which have forms similar to ours, but are hairy and use neither language nor reason. There are imbeciles 2 among us who have exactly the same form as ourselves, but who are destitute of reason, and some of them make no use of language. There are some creatures, as it is said, which, with the use of lan guage and of reason and a form similar in every other respect to ours, have hairy tails; at least, it is not impossible that there are such creatures.3 There are others, where the males have no beard, and others, where the females have. If you ask whether all these creatures are men or not, whether they 1 Cf. New Essays, Preface, ante, p. 52, Bk. III., chap, fi, ante, p. 332, note 2; also letters to Des Bosses, Sept. 20, Oct. 4, 1706, Gerhardt, 2, 310, 319, 2 Locke has: " naturals," PhiloK. Works, Vol. 2, p. 53 (Bohn's ed.)-— TR.
3 The myth of men with tails, here mentioned and accepted as credible hy Locke, arose either from the superficial observation of African travellers, or from their uncritical acceptance and rehearsal of the stories of such Negroes as claimed to have seen such beings, assumed hy them to he endowed with reason, although covered with hair and furnished with tails — stories which seem to rest upon a confusion of men with man-like apes, a confusion the more naturally suggested as many tribes of negroes regard the apes as rational but uncivilized human beings. The myth has been exploded in our day by the knowledge furnished hy scientific explorers into the interior of Africa (the assumed abode of these beings), such as Dr. Georg August Schweinfurth, who states that among the tribes of Central Africa the Dyoor, the Niam-niam, and the Bongo, fasten upon themselves behind, as a part of their dress, the tails of animals, as, for example, that of "the quereza monkey (Colobus)," or tails "composed of the bast of the Sanseviera." Cf. his Im Herzrn von Afrika, English trans, by Ellen E. Frewer, 2 vols., New York: Harper & Bros., 1874, Vol. 1, pp. 201, 294-fi, Vol. 2, pp. 2, 0, 11, 137. — TR.
342 LEIBNITZ'S CRITIQUE OF LOCKE [UK. in belong to the human species, it is plain that the question refers only to the nominal definition, or to the complex idea we have made for ourselves in order to indicate it by this name; for the internal essence is absolutely unknown to us, although we have reason to think that where the faculties, or rather the external figure, are so different, the internal consti tution is not the same.
Th. I think we have in the case of man a definition at once real and nominal. For nothing can be more internal to man than reason, and ordinarily it makes itself well known. There fore the beard and the tail will not be considered in comparison with it. A man of the forest, though hairy, will make himself recognized: and it is not the hair of a inagot l which excludes him. Imbeciles lack the use of reason; but as we know by experience that reason is often bound and cannot appear, and as this happens in the case of men who have exhibited and will exhibit reason, we make, probably, the same judgment regarding these imbeciles upon other indications, i.e. upon their bodily figure. It is only by these signs, united with their birth, that we presume that infants are men, and will manifest reason; and we are seldom deceived. But if there were rational animals with an external form a little different from ours, we should be embarrassed. This shows that our definitions, when dependent upon the exterior of bodies, are imperfect and provisional. If any one called himself an angel, and knew, or knew how to do, things much above us, he might be believed. If some one else, like Gonzales,2 came from the moon by means of some extraordinary machine, and told us credible things about his native country, he would pass