Pure logical thinking cannot yield us any knowledge of the empirical world. All knowledge of reality starts from experience and ends in it.

I know what it's like to see one's mother go through the agony of death and be unable to help; there is no consolation. We all have to bear such heavy burdens, for they are unalterably linked to life.

The conflict that exists today is no more than an old-style struggle for power, once again presented to mankind in semireligious trappings. The difference is that, this time, the development of atomic power has imbued the struggle with a ghostly character; for both parties know and admit that, should the quarrel deteriorate into actual war, mankind is doomed.

The years of anxious searching in the dark, with their intense longing, their alternations of confidence and exhaustion and the final emergence into the light -- only those who have experienced it can understand it.

The more I learn of physics, the more I am drawn to metaphysics.

Time is what the clock says.

The splitting of the atom has changed everything except for how we think.