While we're on the topic of theft from my last post, below are the words of T.S. Elliot on the measure of a poet:

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.

This can be just as easily applied to any act of creation--be it gadget, painting, poem, building, vehicle or song.
The quote above is also the one everyone mis-attributes to Picasso.