a commercium_. They might
be excluded from the possibility of individual ownership in any of
three ways. It might be that from their nature they could only be
used, not owned, and from their nature they were adapted to general
use. These were _res communes_. Or it might be that they were made for
or from their nature they were adapted to public use, that is use for
public purposes by public functionaries or by the political
community. These were _res publicae_. Again it might be because they
had been devoted to religious purposes or consecrated by religious
acts inconsistent with private ownership. Such things were _res
sanctae_, _res sacrae_ and _res religiosae_. In modern law, as a
result of the medieval confusion of the power of the sovereign to
regulate the use of things (_imperium_) with ownership (_dominium_)
and of the idea of the corporate personality of the state, we have
made the second category into property of public corporations. And
this has required modern systematic writers to distinguish between
those things which cannot be owned at all, such as human beings,
things which may be owned by public corporations but may not be
transferred, and things which are owned by public corporations in full
dominion. We are also tending to limit the idea of discovery and
occupation by making _res nullius_ (e.g., wild game) into _res
publicae_ and to justify a more stringent regulation of individual use
of _res communes_ (e.g., of the use of running water for irrigation or
for power) by declaring that they are the property of the state or
are "owned by the state in trust for the people." It should be said,
however, that while in form our courts and legislatures seem thus to
have reduced everything but the air and the high seas to ownership, in
fact the so-called state ownership of _res communes_ and _res nullius_
is only a sort of guardianship for social purposes. It is _imperium_,
not _dominium_. The state as a corporation does not own a river as it
owns the furniture in the state house. It does not own wild game as it
owns the cash in the vaults of the treasury. What is meant is that
conservation of important social resources requires regulation of the
use of _res communes_ to eliminate friction and prevent waste, and
requires limitation of the times when, places where and persons by
whom _res nullius_ may be acquired in order to prevent their
extermination. Our modern way of putting it is only an incident of the
nine