Have all ideas already been thought of ?

Amidst a superb reflection by Jonathan Lethem on ideas, the marketplace, and copyright, consider this section, on ownership of ideas:

Undiscovered public knowledge emboldens us to question the extreme claims to originality made in press releases and publishers' notices: Is an intellectual or creative offering truly novel, or have we just forgotten a worthy precursor? Does solving certain scientific problems really require massive additional funding, or could a computerized search engine, creatively deployed, do the same job more quickly and cheaply? Lastly, does our appetite for creative vitality require the violence and exasperation of another avant-garde, with its wearisome killing-the-father imperatives, or might we be better off ratifying the ecstasy of influence—and deepening our willingness to understand the commonality and timelessness of the methods and motifs available to artists?

The "ecstasy of influence": what a beautiful way to describe the joy of illumination when we read a beautiful theorem, or a profoundly elegant idea, and use it to build something of our own.