You can put up with everything in this world except not with a long stretch of beautiful days.

True observers of nature, although they may think differently, will still agree that everything that is, everything that is observable as a phenomenon, can only exhibit itself in one of two ways. It is either a primal polarity that is able to unify, or it is a primal unity that is able to divide. The operation of nature consists of splitting the united or uniting the divided; this is the eternal movement of systole and diastole of the heartbeat, the inhalation and exhalation of the world in which we live, act, and exist.

I can tell you, honest friend, what to believe: believe life; it teaches better that book or orator.

Art is long, life short, judgment difficult, opportunity transient. To act is easy, to think is hard; to act according to our thought is troublesome. Every beginning is cheerful: the threshold is the place of expectation.

Oh happy he who still can hope in our day to breathe the truth while plunged in seas of error! What we don't know is really what we need, and what we know is of no use to us whatever!

If one doesn't know one's own country, one doesn't have standards for foreign countries.

As soon as any one belongs to a narrow creed in science, every unprejudiced and true perception is gone.