The zestful but scientific exploration of possibilities and of the techniques for realizing them will make our hopes rational, and will set our ideals within the framework of reality, by showing how much of them are indeed realizable.

It is easier to believe that there was nothing before there was something than that there was something before there was nothing.

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.

The scientific doctrine of progress is destined to replace not only the myth of progress, but all other myths of human earthly destiny. It will inevitably become one of the cornerstones of man's theology, or whatever may be the future substitute for theology, and the most important external support for human ethics.

Evolution... is the most powerful and the most comprehensive idea that has ever arisen on Earth.

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.

Evolution is nothing but matter become conscious of itself.