§ 2. We have the Ideas but of three sorts of Substances; 1. God. 2. Finite Intelligences. 3. Bodies. First, God is without beginning, eternal, unalterable, and every where; and therefore concerning his Identity, there can be no doubt. Secondly, Finite Spirits having had each its determinate time and place of beginning to exist, the relation to that time and place will always determine to each of them its Identity as long as it exists.
[318]Thirdly, The same will hold of every Particle of Matter, to which no Addition or Subtraction of Matter being made, it is the same. […] All other things being but Modes or Relations ultimately terminated in Substances, the Identity and Diversity of each particular Existence of them too will be by the same way determined: Only as to things whose Existence is in succession, such as are the Actions of finite Beings, v. g. Motion and Thought, both which consist in a continued train of Succession, concerning their Diversity there can be no question: Because each perishing the moment it begins, they cannot exist in different times, or in different places, as permanent Beings can at different times exist in distant places; and therefore no motion or thought, considered as at different times can be the same, each part thereof having a different beginning of Existence.
§ 3. From what has been said, ’tis easy to discover, what is so much enquired after, the principium Individuationis, and that ’tis plain is Existence it self, which determines a Being of any sort to a particular time and place incommunicable to two Beings of the same kind. This though it seems easier to conceive in simple Substances or Modes; yet when reflected on, is not more difficult in compounded ones, if care be taken to what it is applied; v. g. Let us suppose an Atom, i. e. a continued body under one immutable Superficies, existing in a determined time and place: ’tis evident, that, considered in any instant of its Existence, it is, in that instant, the same with it self. [320]For being, at that instant, what it is, and nothing else, it is the same, and so must continue, as long as its Existence is continued: for so long it will be the same, and no other. In like manner, if two or more Atoms be joined together into the same Mass, every one of those Atoms will be the same, by the foregoing Rule: And whilst they exist united together, the Mass, consisting of the same Atoms, must be the same Mass, or the same Body, let the parts be never so differently jumbled: But if one of these Atoms be taken away, or one new one added, it is no longer the same Mass, or the same Body. In the state of living Creatures, their Identity depends not on a Mass of the same Particles; but on something else. For in them the variation of great parcels of Matter alters not the Identity: An Oak, growing from a Plant to a great Tree, and then lopp’d, is still the same Oak: And a Colt grown up to a Horse, sometimes fat, sometimes lean, is all the while the same Horse: though, in both of these Cases, there may be a manifest change of the parts: So that truly they are not either of them the same Masses of Matter, though they be truly one of them the same Oak, and the other the same Horse. The reason whereof is, that in these two cases of a Mass of Matter, and a living Body, Identity is not applied to the same thing.
§ 4. We must therefore consider wherein an Oak differs from a Mass of Matter, and that seems to me to be in this; that the one is only the Cohesion of Particles of Matter any how united, the other such a disposition of them as constitutes the parts of an Oak; and such an Organization of those parts, as is [322]fit to receive, and distribute nourishment, so as to continue, and frame the Wood, Bark, and Leaves, etc. of an Oak, in which consists the vegetable Life. That being then one Plant, which has such an Organization of Parts in one coherent Body, partaking of one Common Life, it continues to be the same Plant, as long as it partakes of the same Life, though that Life be communicated to new Particles of Matter vitally united to the living Plant, in a like continued Organization, conformable to that sort of Plants. […]
§ 5. The Case is not so much different in Brutes, but that any one may hence see what makes an Animal, and continues it the same. Something we have like this in Machines, and may serve to illustrate it. For Example, what is a Watch? ’Tis plain ’tis nothing but a fit Organization, or Construction of Parts, to a certain end, which, when a sufficient force is added to it, it is capable to attain. If we would suppose this Machine one continued Body, all whose organized Parts were repair’d, increas’d or diminish’d, by a constant Addition or Separation of insensible Parts, with one Common Life, we should have something very much like the Body of an Animal, with this difference, That in an Animal the fitness of the Organization, and the Motion wherein Life consists, begin together, the Motion coming from within; but in Machines the force, coming sensibly from without, is often away, when the Organ is in order, and well fitted to receive it.
§ 6. This also shews wherein the Identity of the same Man consists; viz. in nothing but a participation of the same [324]continued Life, by constantly fleeting Particles of Matter, in succession vitally united to the same organized Body. He that shall place the Identity of Man in any thing else, but like that of other Animals in one fitly organized Body taken in any one instant, and from thence continued under one Organization of Life in several successively fleeting Particles of Matter, united to it, will find it hard, to make an Embryo, one of Years, mad, and sober, the same Man, by any Supposition, that will not make it possible for Seth, Ismael, Socrates, Pilate, St. Austin, and Caesar Borgia to be the same Man. For if the Identity of Soul alone makes the same Man, and there be nothing in the Nature of Matter, why the same individual Spirit may not be united to different Bodies, it will be possible, that those Men, living in distant Ages, and of different Tempers, may have been the same Man: Which way of speaking must be from a very strange use of the Word Man, applied to an Idea, out of which Body and Shape is excluded: And that way of speaking would agree yet worse with the Notions of those Philosophers, who allow of Transmigration, and are of Opinion that the Souls of Men may, for their Miscarriages, be detruded into the Bodies of Beasts, as fit Habitations with Organs suited to the satisfaction of their Brutal Inclinations. But yet I think no body, could he be [326]sure that the Soul of Heliogabalus were in one of his Hogs, would yet say that Hog were a Man or Heliogabalus.
§ 7. ’Tis not therefore Unity of Substance that comprehends all sorts of Identity, or will determine it in every Case: But to conceive, and judge of it aright, we must consider what Idea the Word it is applied to stands for: It being one thing to be the same Substance, another the same Man, and a third the same Person, if Person, Man, and Substance, are three Names standing for three different Ideas […].
§ 8. An Animal is a living organized Body; and consequently, the same Animal, as we have observed, is the same continued Life communicated to different Particles of Matter, as they happen successively to be united to that organiz’d living Body. And whatever is talked of other definitions, ingenuous observation puts it past doubt, that the Idea in our Minds, of which the Sound Man in our Mouths is the Sign, is nothing else but of an Animal of such a certain Form: Since I think I may be confident, that whoever should see a Creature of his own Shape and Make, though it had no more reason all its Life, than a Cat or a Parrot, would call him still a Man; or whoever should hear a Cat or a Parrot discourse, reason, and philosophize, would call or think it nothing but a Cat or a Parrot; and say, the one was a dull irrational Man, and the other a very intelligent rational Parrot. […] For I presume ’tis not the Idea of a thinking or rational Being alone, that makes the Idea of a Man [328]in most Peoples Sense; but of a Body so and so shaped joined to it; and if that be the Idea of a Man, the same successive Body not shifted all at once, must