The definition of genius is taking the complex and making it simple.

As long as there are sovereign nations possessing great power, war is inevitable.

The longing to behold this pre-established harmony [of phenomena and theoretical principles] is the source of the inexhaustible patience and perseverance with which Planck has devoted himself ... The state of mind which enables a man to do work of this kind is akin to that of the religious worshiper or the lover; the daily effort comes from no deliberate intention or program, but straight from the heart.

Without the sense of fellowship with men of like mind... life would have seemed to me empty.

After a certain high level of technical skill is achieved science and art tend to coalesce in aesthetics, plasticity, and form. The greatest scientists are artists as well.

Scientists believe that every occurrence, including the affairs of human beings, is due to the laws of nature. Therefore a scientist cannot be inclined to believe that the course of events can be influenced by prayer, that is, by a supernaturally manifested wish.

Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.