Even truth needs to be clad in new garments if it is to appeal to a new age.

Cautiousness in judgment is nowadays to be recommended to each and every one: if we gained only one incontestable truth every ten years from each of our philosophical writers the harvest we reaped would be sufficient.

Theologians always try to turn the Bible into a book without common sense.

Be attentive, feel nothing in vain, measure and compare: this is the whole law of philosophy.

A good method of discovery is to imagine certain members of a system removed and then see how what is left would behave: for example, where would we be if iron were absent from the world: this is an old example.

So-called professional mathematicians have, in their reliance on the relative incapacity of the rest of mankind, acquired for themselves a reputation for profundity very similar to the reputation for sanctity possessed by theologians.

When an acquaintance goes by I often step back from my window, not so much to spare him the effort of acknowledging me as to spare myself the embarrassment of seeing that he has not done so.