"I have said more than once that I would give all my books to have the fame of having discovered a single useful truth for the good of mankind."

"I have said more than once, that I hold space to be something merely relative, as time is; that I hold it to be an order of coexistences, as time is an order of successions."

"Time is the order of successive phenomena."

"It is not absurd for discerning Europeans . . . to see something today which is not adequately known by the Chinese erudites, and to be able to interpret their ancient books better than the erudites t…"

"Why is there anything at all rather than nothing whatsoever?"