La guerre, c'est un massacre de gens qui ne se connaissent pas, au profit de gens qui se connaissent, mais ne se massacrent pas.
Bizarre, issues 24-31 (1962), p. 102
This apocryphal quote from Paul Valéry is never precisely sourced: neither on the internet nor in the works we have consulted. See: https://www.guichetdusavoir.org/question/voir/52650

Letter to writer André Gide, as quoted in The Tell-Tale Heart: The Life and Works of Edgar Allan Poe (1978) by Julian Symons, Pt. 1, Epilogue

Quelle: An Anthology

Moralités (1932)
Kontext: Science is feasible when the variables are few and can be enumerated; when their combinations are distinct and clear. We are tending toward the condition of science and aspiring to do it. The artist works out his own formulas; the interest of science lies in the art of making science.

Variant translations:
Stupidity is not my strong suit.
Monsieur Teste (1919)
Kontext: Stupidity is not my strong point. I have seen many persons; I have visited several countries; I have taken part in various enterprises without liking them; I have eaten nearly every day; I have had women. I can now recall a few hundred faces, two or three great spectacles, and the substance of perhaps twenty books. I have not retained the best nor the worst of these things: what could stay with me did.

Originally delivered as a lecture (late 1927); Pure Poetry: Notes for a Lecture The Creative Vision (1960)
Kontext: For the musician, before he has begun his work, all is in readiness so that the operation of his creative spirit may find, right from the start, the appropriate matter and means, without any possibility of error. He will not have to make this matter and means submit to any modification; he need only assemble elements which are clearly defined and ready-made. But in how different a situation is the poet! Before him is ordinary language, this aggregate of means which are not suited to his purpose, not made for him. There have not been physicians to determine the relationships of these means for him; there have not been constructors of scales; no diapason, no metronome, no certitude of this kind. He has nothing but the coarse instrument of the dictionary and the grammar. Moreover, he must address himself not to a special and unique sense like hearing, which the musician bends to his will, and which is, besides, the organ par excellence of expectation and attention; but rather to a general and diffused expectation, and he does so through a language which is a very odd mixture of incoherent stimuli.

Writing at the Yalu River (1895) quoted in Of Time, Passion, and Knowledge: Reflections on the Strategy of Existence (1990) by Julius Thomas Fraser, Part 2, Images in Heaven and on the Earth, Ch. IV, The Roots of Time in the Physical World. Sect. 3 The Living Symmetries of Physics
Kontext: You have neither the patience that weaves long lines nor a feeling for the irregular, nor a sense of the fittest place for a thing … For you intelligence is not one thing among many. You … worship it as if it were an omnipotent beast … a man intoxicated on it believes his own thoughts are legal decision, or facts themselves born of the crowd and time. He confuses his quick changes of heart with the imperceptible variation of real forms and enduring Beings.... You are in love with intelligence, until it frightens you. For your ideas are terrifying and your hearts are faint. Your acts of pity and cruelty are absurd, committed with no calm, as if they were irresistible. Finally, you fear blood more and more. Blood and time.

Tel Quel (1943)

Mauvaises Pensées et Autres (1941)

Unsourced

Quelle: The Art of Poetry

Quelle: Unsourced

Quelle: Regards sur le monde actuel [Reflections on the World Today] (1931), pp. 158-159

Preface
Monsieur Teste (1919)

Allez! Tout fuit! Ma présence est poreuse,
La sainte impatience meurt aussi!
As translated by by C. Day Lewis
Charmes ou poèmes (1922)