It seems to me that property cannot be considered an intrinsic part of human nature, not in the way life is, for example. Property defines a relationship between two objects that only has a basis in the minds of humans themselves.
So, the question is, is the defining of this relationship a "rightful" mental act? I.e., when a person claims ownership over an object, whether the situation makes it a valid claim or not, is such a claim generally right? Meaning, in a practical context, are groups of human beings warranted in developing property laws in general, based on some absolute principle, or is property rather, as James Madison called monopolies in general, "among the greatest nuisances in government" (i.e. a necessary evil)?
The reason I am asking, though I'd rather it didn't interfere too much with the answering, is because of how this relates to modern property law, which seems to have developed a sort of righteousness of its own, as though it were based on some intrinsic right to property. If it is true that property rights are only a convention with the intent of forwarding some general purpose of harmony and human development, then the arguments in favour of extended copyright and patents seem much weaker than if property rights are intrinsic.
Obviously, I have my own thoughts on this question, but what I'm really looking for is the thoughts of the "greats". If anyone can give me an idea of the sorts of things wise people have said on the subject of property in general, that would be a great help.