Allegorically, the People are seeking the blessing of the Protector of the People
for their new enterprise. The Protector responds that they "shall do it as
my son would have," i.e., they shall establish the Libertarian society on
the basis of honesty and trust between all. The People dismiss this "son"
as a purely mythic invention, implying cynically that such a world is not possible.
On the other hand, they "must try"; i.e., they have no choice but to
strive for that world whether they believe it possible or not.