The original baby killer

It's a commonly heard expression among writers. The footnoteMaven recently invoked it: Kill your babies. Those sentences you think are the most precious thing on earth - aren't.

Who said it first - in what context?

Style, for example, is not—can never be—extraneous Ornament. You remember, may be, the Persian lover...how to convey his passion he sought a professional letter-writer and purchased a vocabulary charged with ornament, wherewith to attract the fair one as with a basket of jewels. Well, in this extraneous, professional, purchased ornamentation, you have something which Style is not: and if you here require a practical rule of me, I will present you with this: ‘Whenever you feel an impulse to perpetrate a piece of exceptionally fine writing, obey it—whole-heartedly—and delete it before sending your manuscript to press. Murder your darlings.’ -- Sir Arthur Quiller-Couch (1863-1944), On the Art of Writing, 1916. [Emphasis added]

Note, he didn't advise you not to write the sentence in the first place. Give birth to the jewel, then put it aside.

Quiller Couch is best known as the editor of The Oxford Book of English Verse. He also translated the fairy tales of Sleeping Beauty, Beauty and the Beast, Cinderella, and Bluebeard into English, though there were earlier translations.