Is not every true Reformer, by the nature of him, a Priest first of all? He appeals to Heaven’s invisible justice against Earth’s visible force; knows that it, the invisible, is strong and alone strong. He is a believer in the divine truth of things; a seer, seeing through the shows of things; a worshipper, in one way or the other, of the divine truth of things; a Priest, that is. If he be not first a Priest, he will never be good for much as a Reformer.

Thomas Carlyle
Thomas Carlyle (1795-1881) Scottish essayist and historian
Lecture (1840-05-15), “The Hero as Priest,” Home House, Portman Square, London
    (Source)

The lecture notes were collected by Carlyle into On Heroes, Hero-Worship, & the Heroic in History, Lecture 4 (1841).