In America, we are eager to claim ownership: our homes, our ideas, our organs, even our own celebrity. But beneath our nation's proprietary longing looms a troublesome question: what does it mean to own something? More simply: what is property? The question is at the heart of many contemporary controversies, including disputes over who owns everything from genetic material to indigenous culture to music and film on the Internet. To decide if and when genes or culture or digits are a kind of property that can be possessed, we must grapple with the nature of property itself. How does it...