“If intellection and knowledge were mere passion from without, or the bare reception of extraneous and adventitious forms, then no reason could be given at all why a mirror or looking-glass should not understand; whereas it cannot so much as sensibly perceive those images which it receives and reflects to us.”

the complete title is: The Bride Stripped Bare by her Bachelors, Even (The Large Glass), c. 1915 – 1923
Quote from a letter to fr:Jean Suquet (art historian), New York 25 December 1949; as quoted in The Duchamp Book, ed. Gavin Parkinson, Tate Publishing, London 2008 p. 163
1921 - 1950

XI, 26, Parts of this passage has been heavily compared with later statements of René Descartes; in Latin and with a variant translations:
The City of God (early 400s)
Context: We both are, and know that we are, and delight in our being, and our knowledge of it. Moreover, in these three things no true-seeming illusion disturbs us; for we do not come into contact with these by some bodily sense, as we perceive the things outside of us of all which sensible objects it is the images resembling them, but not themselves which we perceive in the mind and hold in the memory, and which excite us to desire the objects. But, without any delusive representation of images or phantasms, I am most certain that I am, and that I know and delight in this. In respect of these truths, I am not at all afraid of the arguments of the Academicians, who say, What if you are deceived? For if I am deceived, I am. For he who is not, cannot be deceived; and if I am deceived, by this same token I am. And since I am if I am deceived, how am I deceived in believing that I am? for it is certain that I am if I am deceived. Since, therefore, I, the person deceived, should be, even if I were deceived, certainly I am not deceived in this knowledge that I am. And, consequently, neither am I deceived in knowing that I know. For, as I know that I am, so I know this also, that I know. And when I love these two things, I add to them a certain third thing, namely, my love, which is of equal moment. For neither am I deceived in this, that I love, since in those things which I love I am not deceived; though even if these were false, it would still be true that I loved false things. For how could I justly be blamed and prohibited from loving false things, if it were false that I loved them? But, since they are true and real, who doubts that when they are loved, the love of them is itself true and real? Further, as there is no one who does not wish to be happy, so there is no one who does not wish [themself] to be [into being]. For how can he be happy, if he is nothing?

कला र जीवन (Art and Life)
Art and Life

The Twelve Beguines

Source: Dream of the Red Chamber (c. 1760), Chapter 5

Source: Nationalism and Culture (1937), Ch. 1 "The Insufficiency of Economic Materialism"
Context: No thinking man in this day can fail to recognise that one cannot properly evaluate an historical period without considering economic conditions. But much more one-sided is the view which maintains that all history is merely the result of economic conditions, under whose influence all other life phenomena have received form and imprint.
There are thousands of events in history which cannot be explained by purely economic reasons, or by them alone. It is quite possible to bring everything within the terms of a definite scheme, but the result is usually not worth the effort. There is scarcely an historical event to whose shaping economic causes have not contributed, but economic forces are not the only motive powers which have set everything else in motion. All social phenomena are the result of a series of various causes, in most cases so inwardly related that it is quite impossible clearly to separate one from the other. We are always dealing with the interplay of various causes which, as a rule, can be clearly recognised but cannot be calculated according to scientific methods.

The Twelve Beguines

Book II, Ch. 11
Essais (1595), Book II