“Who has studied the works of such men as Euler, Lagrange, Cauchy, Riemann, Sophus Lie, and Weierstrass, can doubt that a great mathematician is a great artist? The faculties possessed by such men, varying greatly in kind and degree with the individual, are analogous with those requisite for constructive art. Not every mathematician possesses in a specially high degree that critical faculty which finds its employment in the perfection of form, in conformity with the ideal of logical completeness; but every great mathematician possesses the rarer faculty of constructive imagination.”

Breaking Down the Wall of Silence (Abbruch der Schweigemauer) (1990)

From a book review in The New York Times (9 May 1976) http://select.nytimes.com/gst/abstract.html?res=F40F13FC345E157493CBA9178ED85F428785F9#, also quoted in The American Mathematical Monthly (December 1994)
Context: Biographical history, as taught in our public schools, is still largely a history of boneheads: ridiculous kings and queens, paranoid political leaders, compulsive voyagers, ignorant generals — the flotsam and jetsam of historical currents. The men who radically altered history, the great scientists and mathematicians, are seldom mentioned, if at all.

1895 - 1905
Source: Lettres à un Inconnu, (Notebook II, p. 8) - Aux sources de l'expressionnisme. Presentation par Gabrielle Dufour-Kowalska. Klincksieck, 1999. p. 106

Source: Mathematics without Apologies: Portrait of a Problematic Vocation, 2015, pp. 147-148

Source: Archipelago (1979), Chapter Three, Pt. 5, A "ghost story" as narrated in its entirety by a character in the novel in a small ward gathering.
Context: "The perfect ghost story is the story of Possession," he said, "and that is hypnotism from beyond the grave. This is possible since hypnotism is by the will, and the will is immortal. A number of notable men have been possessed, and all of their lives seem to fit a pattern: the inconsequential early years, the hiatus when they stood where Faust stood, and the decision. And then the rise to power and influence and almost universal honor after they have made the deal. But it is not themselves, it is the devils within them that gain these things. They are the possessed men who do much of the running of the world, and theirs is the most frightening story that can be imagined. But those who watch the great men do not know that they are shells inhabited by ghosts."

Thomas Babington Macaulay, On John Dryden (1828)
Misattributed

On John Dryden (1828)

"Of Founders and the Political Constitution," p. 72
Against Rousseau (1795)