The question of the origin of life is essentially speculative. We have to construct, by straightforward thinking on the basis of very few factual observations, a plausible and self-consistent picture of a process which must have occurred before any of the forms which are known to us in the fossil record could have existed.

The human mind evolved always in the company of the human body, and of the animal body before it was human. The intricate connections of mind and body must exceed our imagination, as from our point of view we are peculiarly prevented from observing them.

It is characteristic of science that the full explanations are often seized in their essence by the percipient scientist long in advance of any possible proof.

The psychology of a complex mind must differ almost as much from that of a simple, mechanized mind as its psychology would from ours; because something that must underlie and perhaps be even greater than sex is involved.

Naturalism aimed at giving the primitive wishes full play but failed because these wishes are too primitive, too infantile, too inconsistent with themselves to be satisfied even by the greatest license.

We will have to give up taking things for granted, even the apparently simple things.

The region of the mysterious is rapidly shrinking.