From his letter of August 13, 1813 to Isaac McPherson:
Stable ownership is the gift of social law, and is given late in the progress of society. It would be curious then, if an idea, the fugitive fermentation of an individual brain, could, of natural right, be claimed in exclusive and stable property. If nature has made any one thing less susceptible than all others of exclusive property, it is the action of the thinking power called an idea, which an individual may exclusively possess as long as he keeps it to himself; but the moment it is divulged, it forces itself into the possession of every one, and the receiver cannot dispossess himself of it. Its peculiar character, too, is that no one possesses the less, because every other possesses the whole of it.
which pretty well reflects the view embodied in the Constitution and my view of the matter, too.
Our current copyright law is an abomination. I have no problem with authors being granted for a limited time the exclusive rights to their works. That it should be a transferrable property with rights of inheritorship and that the license could be renewed indefinitely has no defense in the public good and the public good is the only rationale for the institution of intellectual property in the first place.
By the way, a quotation from the letter above is the subject of a post by James Grimmelmann on the arrogation of it by the Associated Press to its exclusive use. Isn’t that actionable? It’s like building your personal mansion on public land.
