Every theory in philosophy, which is built on pure conjecture, is an elephant; and every theory that is supported partly by fact, and partly by conjecture, is like Nebuchadnezzar's image, whose feet were partly of iron, and partly of clay.

It is a question of fact, whether the influence of motives be fixed by laws of nature, so that they shall always have the same effect in the same circumstances.

Every indication of wisdom, taken from the effect, is equally an indication of power to execute what wisdom planned.

Every conjecture we can form with regard to the works of God has as little probability as the conjectures of a child with regard to the works of an adult.

I sit in my loft with the haves and look out at the have-nots - the bottom of the bottom - and I have to rationalize it, ... Am I pushing out the homeless?

It is the invaluable merit of the great Basle mathematician Leonard Euler, to have freed the analytical calculus from all geometric bounds, and thus to have established analysis as an independent science, which from his time on has maintained an unchallenged leadership in the field of mathematics.

A philosopher is, no doubt, entitled to examine even those distinctions that are to be found in the structure of all languages... in that case, such a distinction may be imputed to a vulgar error, which ought to be corrected in philosophy.