Scientists who think science consists of unprejudiced data-gathering without speculation are merely cows grazing on the pasture of knowledge.

I shall borrow two words used for a slightly different purpose by the great demographer Alfred Lotka to distinguish between the two systems of heredity enjoyed by man: endosomatic or internal heredity for the ordinary or genetical heredity we have in common with animals; and exosomatic or external heredity for the non-genetic heredity that is peculiarly our own - the heredity that is mediated through tradition, by which I mean the transfer of information through non-genetic channels from one generation to the next.

Deductivism in mathematical literature and inductivism in scientific papers are simply the postures we choose to be seen in when the curtain goes up and the public sees us. The theatrical illusion is shattered if we ask what goes on behind the scenes. In real life discovery and justification are almost always different processes.

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

Scientists are entitled to be proud of their accomplishments, and what accomplishments can they call 'theirs' except the things they have done or thought of first? People who criticize scientists for wanting to enjoy the satisfaction of intellectual ownership are confusing possessiveness with pride of possession. Meanness, secretiveness and, sharp practice are as much despised by scientists as by other decent people in the world of ordinary everyday affairs; nor, in my experience, is generosity less common among them, or less highly esteemed.

[A certain class of explanations in science are] analgesics that dull the ache of incomprehension without removing the cause.

It is a truism to say that a good experiment is precisely that which spares us the exertion of thinking: the better it is, the less we have to worry about its interpretation, about what it really means.