I'm reading: The ecstasy of influence: A plagiarism, by Jonathan Lethem, (Harper's Magazine, Feb.2007). Which is how influences flow freely in art and most artists have no problem admitting this (why should they?). Today's strong claims of copyright are based on what he calls "source hypocrisy" (denial of one's sources, refusal to allow one's work to become the source for someone else). In most cases, artists themselves are less hyporcritics than the corporations, trusts, foundations administring their work. Lethem also mentions that Bob Dylan never refused the permission for a sample.
A large, diverse society cannot survive without property; a large, diverse, and modern society cannot flourish without some form of intellectual property. But it takes little reflection to grasp that there is ample value that the term “property” doesn't capture. And works of art exist simultaneously in two economies, a market economy and a gift economy. The cardinal difference between gift and commodity exchange is that a gift establishes a feeling-bond between two people, whereas the sale of a commodity leaves no necessary connection. (....) But a gift makes a connection. There are many examples, the candy or cigarette offered to a stranger who shares a seat on the plane, the few words that indicate goodwill between passengers on the late-night bus. These tokens establish the simplest bonds of social life, but the model they offer may be extended to the most complicated of unions—marriage, parenthood, mentorship. If a value is placed on these (often essentially unequal) exchanges, they degenerate into something else.