We must say that there are as many squares as there are numbers.

Where the senses fail us, reason must step in.

I notice that young men go to the universities in order to become doctors or philosophers or anything, so long as it is a title, and that many go in for those professions who are utterly unfit for them, while others who would be very competent are prevented by business or their daily cares, which keep them away from letters.

We cannot teach people anything; we can only help them discover it within themselves.

I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use.

I have never met a man so ignorant that I couldn't learn something from him.