Did you know that Madeleine L'Engle almost gave up writing when she turned 40 because of discouragement over rejections? "With all the hours I spent writing, I was still not pulling my own weight financially." She discovered, however, that her subconscious wouldn't let her NOT write.
"I had to write. I had no choice in the matter. It was not up to me to say I would stop because I could not. It didn't matter how small or inadequate my talent. If I never had another book published, and it was very clear to me that this was a real possibility, I still had to go on writing." (Source)
A Wrinkle In Time was rejected 26 times before John C. Farrar of Farrar, Straus and Giroux published it. It ended up winning the 1963 Newbery Medal and became a beloved classic.
The Storyteller: Fact, Fiction and the books of Madeleine L'Engle - by Cynthia Zarin on NewYorker.com