The human race will be the cancer of the planet.

Some day no one will have to work more than two days a week... The human being can consume so much and no more. When we reach the point when the world produces all the goods that it needs in two days, as it inevitably will, we must curtail our production of goods and turn our attention to the great problem of what to do with our new leisure.

If I am to be remembered, I hope it will not be primarily for my specialized scientific work, but as a generalist; one to whom, enlarging Terence's words, nothing human and nothing in external nature was alien.

Evolution: The Modern Synthesis.

God is one among several hypotheses to account for the phenomena of human destiny, and it is now proving to be an inadequate hypothesis. To a great many people, including myself, this realization is a great relief, both intellectually and morally. It frees us to explore the real phenomena for which the God hypothesis seeks to account, to define them more accurately, and to work for a more satisfying set of concepts.

The popular and scientific views of "race" no longer coincide. The word "race," as applied scientifically to human groupings, has lost any sharpness of meaning. To-day it is hardly definable in scientific terms, except as an abstract concept which may, under certain conditions, very different from those now prevalent, have been realized approximately in the past and might, under certain other but equally different conditions, be realized in the distant future.

To speculate without facts is to attempt to enter a house of which one has not the key, by wandering aimlessly round and round, searching the walls and now and then peeping through the windows. Facts are the key.