Divide each difficulty into as many parts as is feasible and necessary to resolve it.

It is contrary to reasoning to say that there is a vacuum or space in which there is absolutely nothing.

Perfect numbers like perfect men are very rare.

These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered.

Nothing comes out of nothing.

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

Human wisdom remains always one and the same although applied to the most diverse objects and it is no more changed by their diversity than the sunshine is changed by the variety of objects which it illuminates.