It seems to me that the idea of a personal God is an anthropological concept which I cannot take seriously. I also cannot imagine some will or goal outside the human sphere... Science has been charged with undermining morality, but the charge is unjust. A man's ethical behavior should be based effectually on sympathy, education, and social ties and needs; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.

I want to go when I want. It is tasteless to prolong life artificially. I have done my share, it is time to go. I will do it elegantly.

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.

If you do the same thing over and over again you cannot ever expect a different outcome.

In matters of trust and justice there can be no distinction between big problems and small, for the general principles which determine the conduct of men are indivisible. Whoever is careless with the truth in small matters cannot be trusted in important affairs.

It takes a touch of genius - and a lot of courage to move in the opposite direction.

Each makes this cosmos and its construction the pivot of his emotional life, in order to find in this way peace and security which he can not find in the narrow whirlpool of personal experience.