e
_fundamentum_ of property rights was natural, whereas the _titulus_
of particular property rights was according to positive law. This
distinction is stated clearly by Aquinas:[1] 'The natural right or
just is that which by its very nature is adjusted to or commensurate
with another person. Now this may happen in two ways; first, according
as it is considered absolutely; thus the male by its very nature is
commensurate with the female to beget offspring by her, and a parent
is commensurate with the offspring to nourish it. Secondly, a thing
is naturally commensurate with another person, not according as it
is considered absolutely, but according to something resultant from
it--for instance, the possession of property. For if a particular
piece of land be considered absolutely, it contains no reason why it
should belong to one man more than to another, but if it be considered
in respect of its adaptability to cultivation, and the unmolested use
of the land, it has a certain commensuration to be the property of
one and not of another man, as the Philosopher shows.' Cajetan's
commentary on this article clearly emphasises the distinction between
_fundamentum_ and _titulus_: 'In the ownership of goods two things are
to be discussed. The first is why one thing should belong to one man
and another thing to another. The second is why this particular field
should belong to this man, that field to that man. With regard to
the former inquiry, it may be said that the ownership of things is
according to the law of nations, but with regard to the second, it may
be said to result from the positive law, because in former times one
thing was appropriated by one man and another thing by another.' It
must not be supposed, however, from what we have just said, that there
are no natural titles to property. Labour, for instance, is a title
flowing from the natural law, as also is occupancy, and in certain
circumstances, prescription. All that is meant by the distinction
between _fundamentum_ and _titulus_ is that, whereas it can be clearly
demonstrated by natural law that the goods of the earth, which are
given by God for the benefit of the whole of mankind, cannot be made
use of to their full advantage unless they are made the subject of
private ownership, particular goods cannot be demonstrated to be
the lawful property of this or that person unless some human act
has intervened. This human act need not necessarily be an act of
agreement;