"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 everyone, and the receiver cannot dispossess himself
of it...He who receives an idea from me, receives instructions himself
without lessening mine; as he who lights his taper at mine, receives
light without darkening me.  That ideas should be 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...Inventions then cannot, in nature,
be a subject of property.

"Society may give an exclusive right to the profits arising from them, as
an encouragement to men to pursue ideas which may produce utility, but this
may or may not be done, according to the will and convenience of the
society, without claim or complaint from anybody."

Thomas Jefferson, in Writings of Thomas Jefferson, vol. 6,
H.A. Washington, Ed., 1854, pp. 180-181.

Quoted in the March 1991 Communications of the ACM, in an article
on the subject "Is Information Property?"

Jefferson was the first head of the U.S. Patent Office; later his
views changed and he came to doubt that patents are beneficial.