When a professor suggested Mrs. Paterson consider becoming a writer, she brushed off the suggestion thinking that she
wouldn't want to add another mediocre writer to this world. Being a glorious failure didn't scare me at all, but being just mediocre did.The Book That Changed My Life: Interviews with National Book Award Winners and Finalists, edited by Diane Olsen, p. 159.
What I heard [the professor] say was, If you're not willing to be mediocre, you'll never be anything at all. I think that's a very important lesson to learn, because people always want a guarantee that they're going to be wonderful. But there's no way of knowing you're good, if you don't dare to be mediocre.