Every new opinion, at its starting, is precisely in a minority of one. In one man’s head alone, there it dwells as yet. One man alone of the whole world believes it; there is one man against all men.

Thomas Carlyle (1795-1881) Scottish essayist and historian

Lecture (1840-05-08), “The Hero as Prophet,” Home House, Portman Square, London
    (Source)

The lecture notes were collected by Carlyle into On Heroes, Hero-Worship, & the Heroic in History, Lecture 2 (1841).