All thinking begins with wondering.

Ordinary people seem not to realize that those who really apply themselves in the right way to philosophy are directly and of their own accord preparing themselves for dying and death.

I believe there exists, & I feel within me, an instinct for the truth, or knowledge or discovery, of something of the same nature as the instinct of virtue, & that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them.

Philosophy stands in the same relation to the study of the actual world as masturbation to sexual love.

In the eyes of dialectical philosophy, nothing is established for all times, nothing is absolute or sacred.

Though an atom is invisible, unthinkable, yet in it are the whole power and potency of the universe.