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

Nothing is necessitated whose opposite is possible.

The greatness of a life can only be estimated by the multitude of its actions. We should not count the years, it is our actions which constitute our life.

It is God who is the ultimate reason things, and the Knowledge of God is no less the beginning of science than his essence and will are the beginning of things.

There are also two kinds of truths: truth of reasoning and truths of fact.

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

Nothing is more important than to see the sources of invention which are, in my opinion more interesting than the inventions themselves.