It is always a sign of an unproductive time when it concerns itself with petty and technical aspects [in philology], and likewiseit is a sign of an unproductive person to pursue such trifles.

You must either conquer and rule or serve and lose, suffer or triumph, be the anvil or the hammer.

Experiments are mediators between nature and idea.

All things are only transitory.

Let mental culture go on advancing, let the natural sciences progress in even greater extent and depth, and the human mind widen itself as much as it desires: beyond the elevation and moral culture of Christianity, as it shines forth in the Gospels, it will not go.

Pity on the person who has become accustomed to seeing in necessity something arbitrary, who ascribes to the arbitrary some sort of reason, and even claims that following that sort of reason has religious value.

Life is but a preparation for what there is to come.