“Truth and beauty … yield themselves only to whoever surrenders to them—as to a rescuer.”

Source: Psychologie des Foules [The Crowd: A Study of the Popular Mind] (1895)

"Talk to an Art-Union (A Brooklyn fragment)" http://www.aol.bartleby.com/229/4011.html (1839); later delivered as a lecture at the Brooklyn Art Union (31 March 1851) and printed in the Brooklyn Daily Advertizer (3 April 1851)
Context: It is a beautiful truth that all men contain something of the artist in them. And perhaps it is the case that the greatest artists live and die, the world and themselves alike ignorant what they possess. Who would not mourn that an ample palace, of surpassingly graceful architecture, fill’d with luxuries, and embellish’d with fine pictures and sculpture, should stand cold and still and vacant, and never be known or enjoy’d by its owner? Would such a fact as this cause your sadness? Then be sad. For there is a palace, to which the courts of the most sumptuous kings are but a frivolous patch, and, though it is always waiting for them, not one of its owners ever enters there with any genuine sense of its grandeur and glory.
I think of few heroic actions, which cannot be traced to the artistical impulse. He who does great deeds, does them from his innate sensitiveness to moral beauty.

Light (1919), Ch. XVI - De Profundis Clamavi

Side Effects (1980), My Apology

Source: The House of Hades

1840s, On the Concept of Irony with Continual Reference to Socrates (1841)

Part I, Essay 23: Of The Standard of Taste
Essays, Moral, Political, and Literary (1741-2; 1748)
Source: Of the Standard of Taste and Other Essays
Context: Beauty is no quality in things themselves: It exists merely in the mind which contemplates them; and each mind perceives a different beauty. One person may even perceive deformity, where another is sensible of beauty; and every individual ought to acquiesce in his own sentiment, without pretending to regulate those of others.

Source: Sculpting in Time (1986), p. 162

1900s, "The Study of Mathematics" (November 1907)
Context: Mathematics, rightly viewed, possesses not only truth, but supreme beauty – a beauty cold and austere, like that of sculpture, without appeal to any part of our weaker nature, without the gorgeous trappings of painting or music, yet sublimely pure, and capable of a stern perfection such as only the greatest art can show. The true spirit of delight, the exaltation, the sense of being more than Man, which is the touchstone of highest excellence, is to be found in mathematics as surely as in poetry. What is best in mathematics deserves not merely to be learnt as a task, but to be assimilated as a part of daily thought, and brought again and again before the mind with ever-renewed encouragement.