We would discover upon further investigation that the greater the interdependence of the individuals, the more complex the government.
Confining our attention now to man, whose government is the most complex, we may put our generalization into this form: Man establishes government because _by nature he is a social being_.

This may be taken as the fundamental reason.

Let us now proceed to trace the relation between cause and effect.
In order that people may go from place to place to meet others for pleasure or business, roads are needed.

Some of these roads may cross streams too deep for fording, so bridges must be provided.

These things are for the good of all; they are public needs, and should be provided by the public.