Science is a very human form of knowledge. We are always at the brink of the known; we always feel forward for what is to be hoped. Every judgment in science stands on the edge of error and is personal. Science is a tribute to what we can know although we are fallible.

Has there ever been a society which has died of dissent? Several have died of conformity in our lifetime.

Dissent is the mark of freedom, as originality is the mark of independence of mind. … No one can be a scientist … if he does not have independence of observation and of thought.

The preoccupation with the choice of a mate both by male and female I regard as a continuing echo of the major selective force by which we have evolved.

The child is not a prisoner of its inheritance; it holds its inheritance as a new creation which its future actions will unfold.

Certainty ends inquiry.

We gain our ends only with the laws of nature; we control her only by understanding her laws.