No Dilettantism in this Mahomet; it is a business of Reprobation and Salvation with him, of Time and Eternity: he is in deadly earnest about it! Dilettantism, hypothesis, speculation, a kind of amateur-search for Truth, toying and coquetting with Truth: this is the sorest sin. The root of all other imaginable sins. It consists in the heart and soul of the man never having been open to Truth; — "living in a vain show." Such a man not only utters and produces falsehoods, but is himself a falsehood. The rational moral principle, spark of the Divinity, is sunk deep in him, in quiet paralysis of life-death.

Heroes and Hero-Worship (1840) - The Hero as Prophet