"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. He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me."

Thomas Jefferson (1813)

Consider the quote above. Interpreted by an economist, Jefferson appears to have been arguing that ideas, once they are divulged, are:

(choose the correct option from below)

1) private goods

2) public goods

3) external goods

4) internal goods