— Robert Oppenheimer American theoretical physicist and professor of physics 1904 - 1967
Context: I believe that through discipline, though not through discipline alone, we can achieve serenity, and a certain small but precious measure of the freedom from the accidents of incarnation, and charity, and that detachment which preserves the world which it renounces. I believe that through discipline we can learn to preserve what is essential to our happiness in more and more adverse circumstances, and to abandon with simplicity what would else have seemed to us indispensable; that we come a little to see the world without the gross distortion of personal desire, and in seeing it so, accept more easily our earthly privation and its earthly horror — But because I believe that the reward of discipline is greater than its immediate objective, I would not have you think that discipline without objective is possible: in its nature discipline involves the subjection of the soul to some perhaps minor end; and that end must be real, if the discipline is not to be factitious. Therefore I think that all things which evoke discipline: study, and our duties to men and to the commonwealth, war, and personal hardship, and even the need for subsistence, ought to be greeted by us with profound gratitude, for only through them can we attain to the least detachment; and only so can we know peace.
Letter to his brother Frank (12 March 1932), published in Robert Oppenheimer : Letters and Recollections (1995) edited by Alice Kimball Smith, p. 155