In no case is there a loss of personal existence to deplore. Nor will there ever be. - Erwin Schrödinger

How does the living organism avoid decay? The obvious answer is: By eating, drinking, breathing and (in the case of plants) assimilating. The technical term is metabolism. The Greek word () means change or exchange. Exchange of what?

Our mind, by virtue of a certain finite, limited capability, is by no means capable of putting a question to Nature that permits a continuous series of answers. The observations, the individual results of measurements, are the answers of Nature to our discontinuous questioning.

do the chromosomes behave in ontogenesis?3 The growth of an organism is effected by consecutive cell divisions. Such a cell division is called mitosis. It is, in the life of a cell, not such a very frequent event as one might expect, considering the enormous number of cells of which our body is composed. In the beginning the growth is rapid. The egg divides into two ‘daughter cells’ which, at the next step, will produce a generation of four, then of 8, 16, 32, 64, …, etc. The frequency of division will not remain exactly the same in all parts of the growing body, and that will break the regularity of these numbers. But from their rapid increase we infer by an easy computation that on the average as few as 50 or 60 successive divisions suffice to produce the number of cells4 in a grown man – or, say, ten times the number,2 taking into account the exchange of cells during lifetime. Thus, a body cell of mine is, on the average, only the 50th or 60th ‘descendant’ of the egg that was I.