„If the genius is an artist, then he accomplishes his work as art, but neither he nor his work of art has a telos outside him.“
Source: 1840s, Two Ethical-Religious Minor Essays (1849), P. 108
Related quotes

— Pablo Picasso Spanish painter, sculptor, printmaker, ceramicist, and stage designer 1881 - 1973
Source: 1920s, "Picasso Speaks" (1923), p. 315.
— Ad Reinhardt American painter 1913 - 1967
Source: 1956 - 1967, Art-as-Art Dogma' part II, (1964), p. 155

— Fortunato Depero Italian painter, writer, sculptor and graphic designer 1892 - 1960
p 97.
So I think, so I paint (1947)

— Alfred Stieglitz American photographer 1864 - 1946
'Is Photography a Failure?', Alfred Stieglitz, 'Sun: 5.', March 14, 1922; as quoted on Wikipedia

— Arnold Schoenberg Austrian-American composer 1874 - 1951
"An Artistic Impression" (1909) in Style and Idea (1985), p. 189
1900s

— Francis of Assisi Catholic saint and founder of the Franciscan Order 1182 - 1226
This quote was actually composed by Louis Nizer, and published in his book, Between You and Me (1948).
Misattributed
Variant: He who works with his hands is a laborer. He who works with his hands and his head is a craftsman. He who works with his hands and his head and his heart is an artist.
— Thomas Hodgskin British writer 1787 - 1869
Source: Labour Defended against the Claims of Capital (1825), p. 66

„The artist works out his own formulas; the interest of science lies in the art of making science.“
— Paul Valéry French poet, essayist, and philosopher 1871 - 1945
Moralités (1932)
Context: 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.

— Sadik Kaceli Albanian artist 1914 - 2000
Për nivel të lartë në krijimtari, një kontribut në shquar në artet figurative Shqiptare dhe një ndihmë të pakursyer në përgatitjen e brezave të artistëve të rinj.
Sali Berisha, President of Albania (22-03-1994)

— John F. Kennedy 35th president of the United States of America 1917 - 1963
"LOOK Magazine Article 'The Arts in America' (552)" (18 December 1962) http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations.aspx
1962

„Who science has and art
He has religion too
Who neither of them owns
Religion is his due.“
— Johann Wolfgang von Goethe German writer, artist, and politician 1749 - 1832
Wer Wissenschaft und Kunst besitzt, / Hat auch Religion / Wer jene beiden nicht besitzt / Der habe Religion
As quoted in Jost Lemmerich's "Science and Conscience: The Life of James Franck" (2011), p. 261.
Variant translation: "The man who science has and art, He also has religion. But he who is devoid of both, He surely needs religion." (as quoted in "Homilies of science" by Paul Carus (1892) and The Open Court, Weekly Journal, Vol. II (1887).
Wilhelm Meister's Lehrjahre (Apprenticeship) (1786–1830)

— Bram van Velde Dutch painter 1895 - 1981
Letter to H. E. Kramer, 25-10-1926, as quoted in: Bram van Velde, A Tribute, Municipal Museum De Lakenhal Leiden, Municipal Museum Schiedam, Museum de Wieger, Deurne 1994, p. 44 (English translation: Charlotte Burgmans)
1920's

— Patrick Swift British artist 1927 - 1983
X magazine (1959-62)
Context: It is not necessary to subscribe to the tiresome conception of the artist as rampaging Bohemian to understand that the activity of painting is socially useless, or at best occupies a dubious position... In the remote purity of his solitariness, where the work of art is made, the artist is supremely the anti-social creature.

— Eli Siegel Latvian-American poet, philosopher 1902 - 1978
Everything Has to Do with Hardness and Softness (1969)

— Marianne von Werefkin expressionist painter 1860 - 1938
Vol. 1: 'My beautiful One, My Unique!', pp. 130-140
1895 - 1905, Lettres à un Inconnu, 1901 – 1905; Museo Communale, Ascona