A reality completely independent of the spirit that conceives it, sees it, or feels it, is an impossibility. A world so external as that, even if it existed, would be forever inaccessible to us.

It is not order only, but unexpected order, that has value.

One does not ask whether a scientific theory is true, but only whether it is convenient.

Thought must never submit, neither to a dogma, nor to a party, nor to a passion, nor to an interest, nor to a preconceived idea, nor to whatever it may be, save to the facts themselves, because, for thought, submission would mean ceasing to be.

Later generations will regard Mengenlehre (set theory) as a disease from which one has recovered.

Sociology is the science with the greatest number of methods and the least results.

Hypotheses are what we lack the least.