But revolutions are made by fanatical men of action with one-track minds, geniuses in their ability to confine themselves to a limited field. They overturn the old order in a few hours or days, the whole upheaval takes a few weeks or at most years, but the fanatical spirit that inspired the upheavals is worshipped for decades thereafter, for centuries.

Boris Pasternak (1890-1960) Russian poet, novelist, and literary translator

Doctor Zhivago [До́ктор Жива́го], Part 2, ch. 14 “Return to Varykino,” sec. 14 (1955) [tr. Hayward & Harari (1958), US ed.]
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Alternate translations:

But revolutions are made by fanatical men of action with one-track minds, men who are narrow-minded to the point of genius. They overturn the old order in a few hours or days; the whole upheaval takes a few weeks or at most years, but for decades thereafter, for centuries, the spirit of narrowness which led to the upheaval is worshipped as holy.
[tr. Hayward & Harari (1958), UK ed., "Again Varykino"]

Revolutions are produced by men of action, one-sided fanatics, geniuses of self-limitation. In a few hours or days they overturn the old order. The upheavals last for weeks, for years at the most, and then for decades, for centuries, people bow down to the spirit of limitation that led to the upheavals as to something sacred.
[tr. Pevear & Volokhonsky (2010), "In Varykino Again"]