When the caterpillar emerges from the egg, almost all that was inside the egg has become caterpillar; the shell is nearly empty, and cannot move; therefore we do not count it, and call the caterpillar a continuation of the egg’s existence, and personally identical with the egg. So with the chrysalis and the moth; but after the moth has laid her eggs she can still move her wings about, and she looks nearly as large as she did before she laid them; besides, she may yet lay a few more, therefore we do not consider the moth’s life as continued in the life of her eggs, but rather in their husk, which we still call the moth, and which we say dies in a day or two, and there is an end of it. Moreover, if we hold the moth’s life to be continued in that of her eggs, we shall be forced to admit her to be personally identical with each single egg, and, hence, each egg to be identical with every other egg, as far as the past, and community of memories, are concerned; and it is not easy at first to break the spell which words have cast around us, and to feel that one person may become many persons, and that many different persons may be practically one and the same person, as far as their past experience is concerned; and again, that two or more persons may unite and become one person, with the memories and experiences of both, though this has been actually the case with every one of us.
Our present way of looking at these matters is perfectly right and reasonable, so long as we bear in mind that it is a _façon de parler_, a sort of hieroglyphic which shall stand for the course of nature, but nothing more. Repair (as is now universally admitted by physiologists) is only a phase of reproduction, or rather reproduction and repair are only phases of the same power; and again, death and the ordinary daily waste of tissue, are phases of the same thing. As for identity it is determined in any true sense of the word, not by death alone, but by a combination of death and failure of issue, whether of mind or body.
To repeat. Wherever there is a separate centre of thought and action, we see that it is connected with its successive stages of being, by a series of infinitely small changes from moment to moment, with, perhaps, at times more startling and rapid changes, but, nevertheless, with no such sudden, complete, and unrepaired break up of the preceding condition, as we shall agree in calling death. The branching out from it at different times of new centres of thought and action, has commonly as little appreciable effect upon the parent-stock as the fall of an apple full of ripe seeds has upon an apple-tree; and though the life of the parent, from the date of the branching off of such personalities, is more truly continued in these than in the residuum of its own life, we should find ourselves involved in a good deal of trouble if we were commonly to take this view of the matter. The residuum has generally the upper hand. He has more money, and can eat up his new life more easily than his new life, him. A moral residuum will therefore prefer to see the remainder of his life in his own person, than in that of his descendants, and will act accordingly. Hence we, in common with most other living beings, ignore the offspring as forming part of the personality of the parent, except in so far as that we make the father liable for its support and for its extravagances (than which no greater proof need be wished that the law is at heart a philosopher, and perceives the completeness of the personal identity between father and son) for twenty-one years from birth. In other respects we are accustomed, probably rather from considerations of practical convenience than as the result of pure reason, to ignore the identity between parent and offspring as completely as we ignore personality before birth. With these exceptions, however, the common opinion concerning personal identity is reasonable enough, and is found to consist neither in consciousness of such identity, nor yet in the power of recollecting its various phases (for it is plain that identity survives the distinction or suspension of both these), but in the fact that the various stages appear to the majority of people to have been in some way or other linked together.