There are 400,000 species of beetles on this planet, but only 8,000 species of mammals.

Every Christian church has tried to impose a code of morals of some kind for which it has claimed divine sanction. As these codes have always been opposed to those of the gospels a loophole has been left for moral progress such as hardly exists in other religions.

A fairly bright boy is far more intelligent and far better company than the average adult.

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.

And if we must educate our poets and artists in science, we must educate our masters, labour and capital, in art.

To the biologist the problem of socialism appears largely as a problem of size.

I have come to the conclusion that my subjective account of my motivation is largely mythical on almost all occasions. I don't know why I do things.