Gottfried Wilhelm Leibniz — "Time is the order of successive phenomena."

"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."

"The present is saturated with the past and pregnant with the future."

"Why is there something rather than nothing?"

"I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is actual in nature."

"The universe, if it were not composed of monads, would be a mere aggregate, not a substance."