Today the world changes so quickly that in growing up we take leave not just of youth but of the world we were young in.

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.

Innocent, unbiased observation is a myth.

The bells which toll for mankind are - most of them, anyway - like the bells of Alpine cattle; they are attached to our own necks, and it must be our fault if they do not make a cheerful and harmonious sound.

It can be said with complete confidence that any scientist of any age who wants to make important discoveries must study important problems. Dull or piffling problems yield dull or piffling answers. It is not enough that a problem should be "interesting".

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

There is much else in the literary idiom of nature-philosophy: nothing-buttery, for example, always part of the minor symptomatology of the bogus.