“His judgement demonstrates that one can be a genius and understand nothing of an art that is not one's own.”

Source: Sleepless

Book III, Ch.1
Enquiry Concerning Political Justice (1793)

Interview with Christian Salmon (Fall 1983), Writers at Work: The Paris Review Interviews, Series Seven [Viking, 1988, ], pp. 217-218
Context: Do you realize that people don't know how to read Kafka simply because they want to decipher him? Instead of letting themselves be carried away by his unequaled imagination, they look for allegories — and come up with nothing but clichés: life is absurd (or it is not absurd), God is beyond reach (or within reach), etc. You can understand nothing about art, particularly modern art, if you do not understand that imagination is a value in itself.

Paracelsus the Physician (1942)
Context: No one can flatter himself that he is immune to the spirit of his own epoch, or even that he possesses a full understanding of it. Irrespective of our conscious convictions, each one of us, without exception, being a particle of the general mass, is somewhere attached to, colored by, or even undermined by the spirit which goes through the mass. Freedom stretches only as far as the limits of our consciousness.

Novalis (1829)
Context: When we speak of the aim and Art observable in Shakespeare's works, we must not forget that Art belongs to Nature; that it is, so to speak, self-viewing, self-imitating, self-fashioning Nature. The Art of a well-developed genius is far different from the Artfulness of the Understanding, of the merely reasoning mind. Shakspeare was no calculator, no learned thinker; he was a mighty, many-gifted soul, whose feelings and works, like products of Nature, bear the stamp of the same spirit; and in which the last and deepest of observers will still find new harmonies with the infinite structure of the Universe; concurrences with later ideas, affinities with the higher powers and senses of man. They are emblematic, have many meanings, are simple and inexhaustible, like products of Nature; and nothing more unsuitable could be said of them than that they are works of Art, in that narrow mechanical acceptation of the word.

On War (1832), Book 3

Interview with The Independent (April 15, 2004) https://www.independent.co.uk/news/uk/this-britain/healing-the-world-with-art-560103.html

1860s, Realist Manifesto' - an open letter, 1861

c. 1910; as quoted in: Der Blick auf Fränzi und Marcella: Zwei Modelle der Brücke-Künstler Heckel, Kirchner und Pechstein, Norbert Nobis; Sprengel Museum Hannover und Stiftung Moritzburg, 2011, p 17
1905 - 1915