Body cells replace themselves every month. Even at this very moment. Most everything you think you know about me is nothing more than memories.

Let us admit that no matter how small the chance it could happen, one molecule could be created by such astronomical odds of chance. However, one molecule is of no use. Hundreds of millions of identical ones are necessary. Thus we either admit the miracle or doubt the absolute truth of science.

[M]etabolic flux... Even a simple bacterial cell can undergo... a billion trnasformations per second... is... what being alive is.

The hydrogen atoms in a human body completely refresh every seven years. As we age we are really a river of cosmically old atoms. The carbons in our bodies were produced in the dust of a star. The bulk of matter in our hands, skin, eyes, and hearts was made near the beginning of time, billions of years ago. We are much older than we look.

No two moments are identical in a conscious being

How puzzling all these changes are! I'm never sure what I'm going to be, from one minute to another.

Unlike the everlasting soul, the mind has many parts, it constantly changes, and there is no reason to think it is eternal.

Every second of existence is a new miracle. Consider the countless variations and possibilities that await us every second—avenues into the future. We take only one of these; the others—who knows where they go? This is the eternal marvel, the magnificent uncertainty of the second next to come, with the past a steady unfolding carpet of denouement.

The figure is staggering and its implications are not easily grasped-500 new chemicals to which the bodies of men and animals are required somehow to adapt each year, chemicals totally outside the limits of biologic experience.

PLEASE BELIEVE that I am falling apart. I am not speaking metaphorically; nor is this the opening gambit of some melodramatic, riddling, grubby appeal for pity. I mean quite simply that I have begun to crack all over like an old jug — that my poor body, singular, unlovely, buffeted by too much history, subjected to drainage above and drainage below, mutilated by doors, brained by spittoons, has started coming apart at the seams. In short, I am literally disintegrating, slowly for the moment, although there are signs of acceleration. I ask you only to accept (as I have accepted) that I shall eventually crumble into (approximately) six hundred and thirty million particles of anonymous, and necessarily oblivious, dust.

We live through myriads of seconds, but there is only one second among all these myriads which brings our whole inner world to the boil; the second in which, as Stendhal described, there suddenly takes place a crystallization in the supersaturated blood; a magical second like that of procreation, and, like it, hidden in the warm interior of one's own body, invisible, intangible, impalpable, a unique experience of mystery. No algebra of the soul can calculate it; no alchemy can divine it. Usually, even for ourselves, it remains unsearchable.

For instance, the scientific article may say, 'The radioactive phosphorus content of the cerebrum of the rat decreases to one- half in a period of two weeks.' Now what does that mean?
It means that phosphorus that is in the brain of a rat — and also in mine, and yours — is not the same phosphorus as it was two weeks ago. It means the atoms that are in the brain are being replaced: the ones that were there before have gone away.
So what is this mind of ours: what are these atoms with consciousness? Last week's potatoes! They now can remember what was going on in my mind a year ago — a mind which has long ago been replaced. To note that the thing I call my individuality is only a pattern or dance, that is what it means when one discovers how long it takes for the atoms of the brain to be replaced by other atoms. The atoms come into my brain, dance a dance, and then go out — there are always new atoms, but always doing the same dance, remembering what the dance was yesterday.

Every person is destroyed when we cease to see him; after which his next appearance is a new creation, different from that which immediately preceded it, if not from them all.

From one moment to another one can lose heart.