Most often attributed in the English-speaking world to Aldous Huxley in Eyeless in Gaza, but his character actually says he's quoting:
Chastity—the most unnatural of all the sexual perversions, he added parenthetically, out of Rémy de Gourmont.
After looking at several French-language quotation sites for quotes "out of" this writer (whom i never heard of before today, uncultured boor that i am), i come up with no evidence that he ever said anything like this.
And learn that, in the Francophone world, this quote is universally attributed to George Bernard Shaw! Who seems unlikely to have said this, and no English-language site says that he did.
But i could swear that i first encountered this phrase in French (with, as i recall, "la plus étrange", not anything about "unnatural"), quoted by an English-language writer. I would guess it might have been AC, or perhaps Gershon Legman, another one of my early sources (age 10-13) of information about less common sexual activities.
Some very learned folks lurk, and sometimes even post, here- can anyone help with the original source of this classic line?
I have what looks like the original of my quote, from Gourmont's Physique de l'amour: essai sur l'instinct sexuel (1903), as translated by Ezra Pound as The natural philosophy of love (1922). From chapter XVIII:
De toutes les aberrations sexuelles, la plus singulière est peut-être encore la chasteté./Of all sexual aberrations perhaps the most curious is chastity.
Much thanks to my occasional anonymous Australian correspondent (an ex-poster here), who emailed me overnight after seeing my post.
Chastity is likened to 'mercy', the unmerciful faux kindness of never thinking beyond one's next meal, being un-real. It's good for limpdick tuats tho.
Rules, like belts, are Great for tasteless eunuchs.