Albert Schweitzer: Doing

Variant: Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful.

Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics
Context: Affirmation of the world, which means affirmation of the will-to-live that manifests itself around me, is only possible if I devote myself to other life. From an inner necessity, I exert myself in producing values and practising ethics in the world and on the world even though I do not understand the meaning of the world. For in world- and life-affirmation and in ethics I carry out the will of the universal will-to-live which reveals itself in me. I live my life in God, in the mysterious divine personality which I do not know as such in the world, but only experience as mysterious Will within myself.
Rational thinking which is free from assumptions ends therefore in mysticism. To relate oneself in the spirit of reverence for life to the multiform manifestations of the will-to-live which together constitute the world is ethical mysticism. All profound world-view is mysticism, the essence of which is just this: that out of my unsophisticated and naïve existence in the world there comes, as a result of thought about self and the world, spiritual self-devotion to the mysterious infinite Will which is continuously manifested in the universe.

Reverence for Life (1969)
Context: I do not want to frighten you by telling you about the temptations life will bring. Anyone who is healthy in spirit will overcome them. But there is something I want you to realize. It does not matter so much what you do. What matters is whether your soul is harmed by what you do. If your soul is harmed, something irreparable happens, the extent of which you won't realize until it will be too late.

Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics
Context: The restoration of our world-view can come only as a result of inexorably truth-loving and recklessly courageous thought. Such thinking alone is mature enough to learn by experience how the rational, when it thinks itself out to a conclusion, passes necessarily over into the non-rational. World- and life-affirmation and ethics are non-rational. They are not justified by any corresponding knowledge of the nature of the world, but are the disposition in which, through the inner compulsion of our will-to-live, we determine our relation to the world.
What the activity of this disposition of ours means in the evolution of the world, we do not know. Nor can we regulate this activity from outside; we must leave entirely to each individual its shaping and its extension. From every point of view, then, world- and life-affirmation and ethics are non-rational, and we must have the courage to admit it.

The Problem of Peace (1954)
Context: We have learned to tolerate the facts of war: that men are killed en masse — some twenty million in the Second World War — that whole cities and their inhabitants are annihilated by the atomic bomb, that men are turned into living torches by incendiary bombs. We learn of these things from the radio or newspapers and we judge them according to whether they signify success for the group of peoples to which we belong, or for our enemies. When we do admit to ourselves that such acts are the results of inhuman conduct, our admission is accompanied by the thought that the very fact of war itself leaves us no option but to accept them. In resigning ourselves to our fate without a struggle, we are guilty of inhumanity.

Source: The Spiritual Life (1947), p. 267
Context: The ethic of reverence for life constrains all, in whatever walk of life they may find themselves, to busy themselves intimately with all the human and vital processes which are being played out around them, and to give themselves as men to the man who needs human help and sympathy. It does not allow the scholar to live for his science alone, even if he is very useful to the community in so doing. It does not permit the artist to exist only for his art, even if he gives inspiration to many by its means. It refuses to let the business man imagine that he fulfills all legitimate demands in the course of his business activities. It demands from all that they should sacrifice a portion of their own lives for others. In what way and in what measure this is his duty, this everyone must decide on the basis of the thoughts which arise in himself, and the circumstances which attend the course of his own life. The self-sacrifice of one may not be particularly in evidence. He carries it out simply by continuing his normal life. Another is called to some striking self-surrender which obliges him to set on one side all regard for his own progress. Let no one measure himself by his conclusions respecting someone else. The destiny of men has to fulfill itself in a thousand ways, so that goodness may be actualized. What every individual has to contribute remains his own secret. But we must all mutually share in the knowledge that our existence only attains its true value when we have experienced in ourselves the truth of the declaration: 'He who loses his life shall find it.

Source: The Spiritual Life (1947), p. 164
Context: Anyone who proposes to do good must not expect people to roll stones out of his way, but must accept his lot calmly if they even roll a few more upon it. A strength which becomes clearer and stronger through its experience of such obstacles is the only strength that can conquer them. Resistance is only a waste of strength.

Source: The Quest of the Historical Jesus

Source: Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics, Chapter 26

Source: The Spiritual Life (1947), p. 309

Source: The Spiritual Life (1947), p. 304

Ch. VII, Social Problems in the Forest, p. 130 https://archive.org/stream/ontheedgeofthepr007259mbp#page/n163/mode/2up (1924 translation by Ch. Th. Campion); Schweitzer later repudiated such statements, saying "The time for speaking of older and younger brothers has passed.", as quoted in [Forrow, Lachlan, Foreword, Russell, C.E.B., African Notebook, Syracuse University Press, Albert Schweitzer library, 2002, 978-0-8156-0743-4, http://books.google.com/books?id=qa-TVXEkY3sC&pg=PR13, 23 June 2017, xiii]
Variant:
The African is my brother — but he is my younger brother by several centuries.
As quoted in The Observer (23 October 1955)
On the Edge of the Primeval Forest (1922)