In all sensation we pick and choose, interpret, seek and impose order, and devise and test hypotheses about what we witness. Sense data are taken, not merely given: we learn to perceive.... The teacher has forgotten, and the student himself will soon forget, that what he sees conveys no information until he knows beforehand the kind of thing he is expected to see.

To abdicate from the rule of reason and substitute for it an authentication of belief by the intentness and degree of conviction with which we hold it can be perilous and destructive. Religious beliefs give a spurious spiritual dimension to tribal enmities.

To deride the hope of progress is the ultimate fatuity, the last word in poverty of spirit and meanness of mind.

The alternative to thinking in evolutionary terms is not to think at all.

Ask a scientist what he conceives the scientific method to be and he will adopt an expression that is at once solemn and shifty-eyed: solemn, because he feels he ought to declare an opinion; shifty-eyed, because he is wondering how to conceal the fact that he has no opinion to declare.

It is high time that laymen abandoned the misleading belief that scientific enquiry is a cold dispassionate enterprise, bleached of imaginative qualities, and that a scientist is a man who turns the handle of discovery; for at every level of endeavour scientific research is a passionate undertaking and the Promotion of Natural Knowledge depends above all on a sortee into what can be imagined but is not yet known.

An experiment not worth doing is not worth doing well.