§ 27. Wherein then, would I gladly know, consist the precise and unmovable boundaries of that species? It is plain, if we examine, there is no such thing made by nature, and established by her amongst men. The real essence of that, or any other sort of substances, it is evident we know not; and therefore are so undetermined in our nominal essences, which we make ourselves, that if several men were to be asked concerning some oddly shaped fœtus, as soon as born, whether it were a man or no, it is past doubt, one should meet with different answers. Which could not happen, if the nominal essences, whereby we limit and distinguish the species of substances, were not made by man, with some liberty; but were exactly copied from precise boundaries set by nature, whereby it distinguished all substances into certain species. Who would undertake to resolve, what species that monster was of, which is mentioned by Licetus, lib. i. c. 3. with a man’s head and hog’s body? Or those other, which to the bodies of men had the heads of beasts, as dogs, horses, &c. If any of these creatures had lived, and could have spoke, it would have increased the difficulty. Had the upper part, to the middle, been of human shape, and all below swine; had it been murder to destroy it? Or must the bishop have been consulted, whether it were man enough to be admitted to the font or no? as, I have been told, it happened in France some years since, in somewhat a like case. So uncertain are the boundaries of species of animals to us, who have no other measures than the complex ideas of our own collecting; and so far are we from certainly knowing what a man is; though, perhaps it will be judged great ignorance to make any doubt about it. And yet, I think, I may say, that the certain boundaries of that species are so far from being determined, and the precise number of simple ideas, which make the nominal essence, so far from being settled and perfectly known, that very material doubts may still arise about it. And I imagine, none of the definitions of the word man, which we yet have, nor descriptions of that sort of animal, are so perfect and exact, as to satisfy a considerate inquisitive person; much less to obtain a general consent, and to be that which men would every-where stick by, in the decision of cases, and determining of life and death, baptism, or no baptism, in productions that might happen.
§ 24. Fourthly, the mistake is yet greater, when I judge, that this complex idea contains in it the real essence of any body existing, when at least it contains but some few of those properties which flow from its real essence and constitution. I say, only some few of those properties; for those properties consisting mostly in the active and passive powers it has, in reference to other things, all that are vulgarly known of any one body of which the complex idea of that kind of things is usually made, are but a very few, in comparison of what a man, that has several ways tried and examined it, knows of that one sort of things: and all that the most expert man knows are but a few, in comparison of what are really in that body, and depend on its internal or essential constitution. The essence of a triangle lies in a very little compass, consists in a very few ideas: three lines including a space make up that essence: but the properties that flow from this essence are more than can be easily known or enumerated. So I imagine it is in substances, their real essences lie in a little compass, though the properties flowing from that internal constitution are endless.
Another famous example is the riddle of the sphinx from Sophocles' .
At length the happy revolution in 1688, effected by the courage and good conduct of the prince of Orange, opened a way for Mr. Locke’s return into his own country; whither he came in the fleet which conveyed the princess of Orange. And upon the restoration of public liberty, he thought it proper to assert his own private rights. He endeavoured therefore to procure his restoration to his place of student of Christ-Church; not that he designed to return thither, but only that it might appear from thence, that he had been unjustly deprived of it. But when he found, that the college could not be prevailed on to dispossess the person who had been elected in his room, and that they would only admit him as a supernumerary student, he desisted from his claim.