An attempt to study the evolution of living organisms without reference to cytology would be as futile as an account of stellar evolution which ignored spectroscopy.

Reality is the cage of those who lack imagination.

Capitalism, though it may not always give the scientific worker a living wage, will always protect him, as being one of the geese which produce golden eggs for its table.

In fact, words are well adapted for description and the arousing of emotion, but for many kinds of precise thought other symbols are much better.

I am quite sure that our views on evolution would be very different had biologists studied genetics and natural selection before and not after most of them were convinced that evolution had occurred.

It seems to me immensely unlikely that mind is a mere by-product of matter. For if my mental processes are determined wholly by the motions of atoms in my brain I have no reason to suppose that my beliefs are true. They may be sound chemically, but that does not make them sound logically. And hence I have no reason for supposing my brain to be composed of atoms.

We do not know, in most cases, how far social failure and success are due to heredity, and how far to environment. But environment is the easier of the two to improve.