One of the surest tests [of the superiority or inferiority of a poet] is the way in which a poet borrows. Immature poets imitate; mature poets steal; bad poets deface what they take, and good poets make it into something better, or at least something different. The good poet welds his theft into a whole of feeling which is unique, utterly different than that from which it is torn; the bad poet throws it into something which has no cohesion. A good poet will usually borrow from authors remote in time, or alien in language, or diverse in interest.
Eliot, T.S., “Philip Massinger,” The Sacred Wood, New York: Bartleby.com, 2000
Here is a background explanation of the "good poets borrow, great poets steal" quote. Or, in the art world, "good artists borrow, great artists steal" often attributed to Picasso. It's also important to note that T.S. Eliot did note mean stealing the work of others and calling it your own. He talks about using work that inspires you in an influential way by adding your own take on the idea and therefore, contributing something new to the community.