We have considered the question of personal identity so as to see whether, without abuse of terms, we can claim it as existing between any two generations of living agents (and if between two, then between any number up to infinity), and we found that we were not only at liberty to claim this, but that we are compelled irresistibly to do so, unless, that is to say, we would think very differently concerning personal identity than we do at present. We found it impossible to hold the ordinary common sense opinions concerning personal identity, without admitting that we are personally identical with all our forefathers, who have successfully assimilated outside matter to themselves, and by assimilation imbued it with all their own memories; we being nothing else than this outside matter so assimilated and imbued with such memories. This, at least, will, I believe, balance the account correctly.

A few remarks upon the assimilation of outside matter by living organisms may perhaps be hazarded here.

Life and Habit — Part 76

As long as any living organism can maintain itself in a position to which it has been accustomed, more or less nearly, both in its own life and in those of its forefathers, nothing can harm it. As long as the organism is familiar with the position, and remembers its antecedents, nothing can assimilate it. It must be first dislodged from the position with which it is familiar, as being able to remember it, before mischief can happen to it. Nothing can assimilate living organism.

Life and Habit — Part 76

On the other hand, the moment living organism loses sight of its own position and antecedents, it is liable to immediate assimilation, and to be thus familiarised with the position and antecedents of some other creature. If any living organism be kept for but a very short time in a position wholly different from what it has been accustomed to in its own life, and in the lives of its forefathers, it commonly loses its memories completely, once and for ever; but it must immediately acquire new ones, for nothing can know nothing; everything must remember either its own antecedents, or some one else’s. And as nothing can know nothing, so nothing can believe in nothing.

Life and Habit — Part 76

A grain of corn, for example, has never been accustomed to find itself in a hen’s stomach—neither it nor its forefathers. For a grain so placed leaves no offspring, and hence cannot transmit its experience. The first minute or so after being eaten, it may think it has just been sown, and begin to prepare for sprouting, but in a few seconds, it discovers the environment to be unfamiliar; it therefore gets frightened, loses its head, is carried into the gizzard, and comminuted among the gizzard stones. The hen succeeded in putting it into a position with which it was unfamiliar; from this it was an easy stage to assimilating it entirely. Once assimilated, the grain ceases to remember any more as a grain, but becomes initiated into all that happens to, and has happened to, fowls for countless ages. Then it will attack all other grains whenever it sees them; there is no such persecutor of grain, as another grain when it has once fairly identified itself with a hen.