We now know that a life which goes excessively against natural impulse is one which is likely to involve effects of strain that may be quite as bad as indulgence in forbidden impulses would have been. People who live a life which is unnatural beyond a point are likely to be filled with envy, malice and all uncharitableness. They may develop strains of cruelty, or, on the other hand, they may so completely lose all joy in life that they have no longer any capacity for effort.

Bertrand Russell (1872-1970) English mathematician and philosopher

Lecture (1948-12-26), “Social Cohesion and Human Nature,” Reith Lecture, No. 1, BBC Radio
    (Source)

As collected, with edits, in Authority and the Individual (1949).