“The master-hand of Nature is supreme.”

As quoted in Rembrandt Drawings (1975) by Paul Némo, as translated by David Macrae
undated quotes

R.U.R. (1920)

translation from Dutch, Fons Heijnsbroek, 2018
version in original Dutch / citaat van J. H. Weissenbruch, in het Nederlands: Ik herinner me, dat ik als jongen in onze museums voor de schilderijen van de oude meesters verstomd stond, zoals ze de natuur tot je lieten spreken. Als ik van iemand geleerd heb de natuur te zien dan is het van onze oude meesters. Maar het meest van de natuur-zelve.
in an interview with J.H. Rössing, at the end of his life, c. 1902; as cited in Eind goed Al goed, de carriere van J.H. Weissenbruch https://www.artsalonholland.nl/grote-meesters-kunstgeschiedenis/johan-hendrik-weissenbruch-haagse-school, by Sander Kletter

Art
Bartlett's Familiar Quotations, 10th ed. (1919)
Variant: In the vaunted works of Art
The master-stroke is Nature's part. 5.

[in 1956, Reinhardt is quoting Paul Cézanne here freely]
1956 - 1967
Source: Pax, no. 13, 1960; as quoted in Abstract Expressionism: Creators and Critics, ed. Clifford Ross, Abrahams Publishers, New York 1990, p. 150

Nobel lecture (1970)
Context: We, holding Art in our hands, confidently consider ourselves to be its masters; boldly we direct it, we renew, reform and manifest it; we sell it for money, use it to please those in power; turn to it at one moment for amusement — right down to popular songs and night-clubs, and at another — grabbing the nearest weapon, cork or cudgel — for the passing needs of politics and for narrow-minded social ends. But art is not defiled by our efforts, neither does it thereby depart from its true nature, but on each occasion and in each application it gives to us a part of its secret inner light.

Heath's book of Beauty, 1833 (1832)

Kakuzō Okakura, The Book of Tea (1906), Ch. II.