It's very good for an idea to be commonplace. The important thing is that a new idea should develop out of what is already there so that it soon becomes an old acquaintance. Old acquaintances aren't by any means always welcome, but at least one can't be mistaken as to who or what they are.
Penelope Fitzgerald (17 December 1916 - 28 April 2000) was an English poet, novelist and biographer. She was the daughter of Edward Knox, one of the four Knox Brothers about whom she wrote a book.