There are also two kinds of truths, those of reasoning and those of fact. Truths of reasoning are necessary and their opposite is impossible, and those of fact are contingent and their opposite is possible. When a truth is necessary its reason can be found by analysis, resolving it into more simple ideas and truths until we reach those which are primitive.

The knowledge which we have acquired ought not to resemble a great shop without order, and without an inventory; we ought to know what we possess, and be able to make it serve us in need.

Imaginary numbers are a fine and wonderful refuge of the divine spirit almost an amphibian between being and non-being.

Every substance is as a world apart, independent of everything else except God.

God's relation to spirits is not like that of a craftsman to his work, but also like that of a prince to his subjects.

I am convinced that the unwritten knowledge scattered among men of different callings surpasses in quantity and in importance anything we find in books, and that the greater part of our wealth has yet to be recorded.

Music is nothing but unconscious arithmetic.