“A novel, or indeed any work of art, is not intended to be a literal transcription from Nature.”

Nirgends erweist sich einem Kunstwerk oder einer Kunstform gegenüber die Rücksicht auf den Aufnehmenden für deren Erkenntnis fruchtbar. Nicht genug, dass jede Beziehung auf ein bestimmtes Publikum oder dessen Repräsentanten vom Wege abführt, ist sogar der Begriff eines "idealen" Aufnehmenden in allen kunsttheoretischen Erörterungen vom Übel, weil diese lediglich gehalten sind, Dasein und Wesen des Menschen überhaupt vorauszusetzen. So setzt auch die Kunst selbst dessen leibliches und geistiges Wesen voraus—seine Aufmerksamkeit aber in keinem ihrer Werke. Denn kein Gedicht gilt dem Leser, kein Bild dem Beschauer, keine Symphonie der Hörerschaft.
The Task of the Translator (1920)

“An Unread Book”, p. 47
The Third Book of Criticism (1969)

to Werner Drewes, 10 April 1933; as quoted in 'Klee & Kandinsky', 2015 exhibition text, Lenbachhaus und Kunstbau Munich, 2015-2016 https://www.zpk.org/en/exhibitions/review_0/2015/klee-kandinsky-969.html
both were closely connected with the Bauhaus, closed by the Nazi-regime in 1933
1930 - 1944

Attributed without citation at The Art Story http://www.theartstory.org/artist-modigliani-amedeo.htm.

The Origins of Art (1966)
Other Quotes
Context: What I am searching for... is some formula that would combine individual initiative with universal values, and that combination would give us a truly organic form. Form, which we discover in nature by analysis, is obstinately mathematical in its manifestations—which is to say that creation in art requires thought and deliberation. But this is not to say that form can be reduced to a formula. In every work of art it must be re-created, but that too is true of every work of nature. Art differs from nature not in its organic form, but in its human origins: in the fact that it is not God or a machine that makes a work of art, but an individual with his instincts and intuitions, with his sensibility and his mind, searching relentlessly for the perfection that is neither in mind nor in nature, but in the unknown. I do not mean this in an other-worldly sense, only that the form of the flower is unknown to the seed.

Source: The Theater and Its Double

1911 - 1940, Notes on Painting - Edward Hopper (1933)

"The Waiting" translated by James E. Irby (1959)

Congressional speech (1849)
Context: I affirm, in words as true and literal as any that belong to geometry, that the man who withholds knowledge from a child not only works diabolical miracles for the destruction of good, but for the creation of evil also. He who shuts out truth, by the same act opens the door to all the error that supplies its place. Ignorance breeds monsters to fill up all the vacuities of the soul that are unoccupied by the verities of knowledge. He who dethrones the idea of law, bids chaos welcome in its stead. Superstition is the mathematical complement of religious truth; and just so much less as the life of a human being is reclaimed to good, just so much more is it delivered over to evil. The man or the institution, therefore, that withholds knowledge from a child, or from a race of children, exercises the awful power of changing the world in which they are to live, just as much as though he should annihilate all that is most lovely and grand in this planet of ours, or transport the victim of his cruelty to some dark and frigid zone of the universe, where the sweets of knowledge are unknown, and the terrors of ignorance hold their undisputed and remorseless reign.