112 
POLITICAL ECONOMY 
To complete this chapter a few remarks 
may be offered as to the various sorts of 
monopoly which are found in the world. 
Monopolies may be classified into natural, 
social, legal, and voluntary. Natural mono 
polies arise out of the limited sources of some 
natural products. Social monopolies are occa 
sioned by the peculiar relations of certain 
businesses to the social economy. For 
instance, it might not be possible for two 
remunerative railway lines to be laid down 
connecting two places ; and, even if it were, 
two lines would be less economical than one 
line. Again, competing gas companies cannot 
be permitted to lay their pipes in the same 
streets. Many social monopolies are now 
in the hands of public authorities. Legal 
monopolies are those maintained by law like 
patents and copyrights, which are defensible 
on the ground that without them much 
valuable inventing and writing would be 
so scantily rewarded as to be in effect 
discountenanced instead of encouraged. 
Many of the social monopolies enjoy legal 
support. Voluntary monopolies arise mainly 
out of combination. Among them we may 
distinguish the monopolies which leave much 
of the individuality of the combining units 
untouched, and those which destroy it. The