“Emulation can be positive, if you succeed in avoiding imitation.”

Hawthorne and His Mosses (1850)
Context: It is better to fail in originality, than to succeed in imitation. He who has never failed somewhere, that man can not be great. Failure is the true test of greatness.
Context: It is better to fail in originality, than to succeed in imitation. He who has never failed somewhere, that man can not be great. Failure is the true test of greatness. And if it be said, that continual success is a proof that a man wisely knows his powers, — it is only to be added, that, in that case, he knows them to be small. Let us believe it, then, once for all, that there is no hope for us in these smooth pleasing writers that know their powers.

On art versus life in “Berkeley world premiere for Naomi Iizuka play” https://www.sfgate.com/performance/article/Berkeley-world-premiere-for-Naomi-Iizuka-play-3271229.php in SF Gate (2010 Mar 4)

interview at Johns' studio, Billy Klüver, March 1963, as quoted in Jasper Johns, Writings, sketchbook Notes, Interviews, ed. Kirk Varnedoe, Moma New York, 1996, p. 87
1960s

Politics and the English Language (1946)

Source: Yoga-Sutras

Titian's remark to Francesco Vargas, the Spanish envoy, c. 1545; in Vicus, De studiorum ratione, u. s. p. 109; as quoted by J.A.Y. Crowe & G.B. Cavalcaselle in Titian his life and times - With some account..., publisher John Murray, London, 1877, p. 115
1541-1576

Variant: You should never be so involved with your position/job that when the position is gone your entire self image is gone with it.