The great majority of us are required to live a life of constant, systematic duplicity. Your health is bound to be affected if, day after day, you say the opposite of what you feel, if you grovel before what you dislike and rejoice at what brings you nothing but misfortune. Your nervous system isn’t a fiction, it’s a part of your physical body, and your soul exists in space and is inside you, like the teeth in your head. You can’t keep violating it with impunity.

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

Doctor Zhivago [До́ктор Жива́го], Part 2, ch. 15 “Conclusion,” sec. 6 [Yury] (1955) [tr. Hayward & Harari (1958), UK ed.]
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Alternate translations:

The great majority of us are required to live a life of constant, systematic duplicity. Your health is bound to be affected if, day after day, you say the opposite of what you feel, if you grovel before what you dislike and rejoice at what brings you nothing but misfortune. Our nervous system isn’t just a fiction, it’s a part of our physical body, and our soul exists in space and is inside us, like the teeth in our mouth. It can’t be forever violated with impunity.
[tr. Hayward & Harari (1958), US ed.]

A constant, systematic dissembling is required of the vast majority of us. It’s impossible, without its affecting your health, to show yourself day after day contrary to what you feel, to lay yourself out for what you don’t love, to rejoice over what brings you misfortune. Our nervous system is not an empty sound, not a fiction. It’s a physical body made up of fibers. Our soul takes up room in space and sits inside us like the teeth in our mouth. It cannot be endlessly violated with impunity.
[tr. Pevear & Volokhonsky (2010)]