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. That ideas should freely spread from one to another over the globe, for the moral and mutual instruction of man, and improvement of his condition, seems to have been peculiarly and benevolently designed by nature, when she made them, like fire, expansible over all space, without lessening their density in any point, and like the air in which we breathe, move, and have our physical being, incapable of confinement or exclusive appropriation. Inventions then cannot, in nature, be a subject of property.Jefferson recognized, however, that a right in social law to what we now call "intellectual property" might be justified on utilitarian grounds. Nevertheless, the natural law regarding ideas is that they may not be owned.
To the extent that the law tries to be realistic and take the nature of things into account, all laws are more or less "natural" even if not purely so. What makes pure natural law so problematic in practice is that in most cases the argument is derived from nothing so simple as the nature of ideas but from human nature -- which is complex, not well understood and varies a bit from one human individual to the next making generalization difficult. Social law, derived from politics, fills the gaps in our understandings although it sometimes also represents unwise attempts to deny the nature of things.
The advantage of natural law, where it can be correctly determined, is that it is by definition realistic insofar as not being in conflict with nature. It is less prone than social law to fail due to unanticipated problems when tested against reality. Patent and copyright law is a mess -- full of arbitrary distinctions and determinations and endless disputes and controversies. This is the natural result of being so artificial.