From any vocabulary of ideas we can build other ideas by formal combinations of signs. But not any set of ideas will be instructive. One must have the right ideas.
Every man should make his son or daughter learn some useful trade or profession, so that in these days of changing fortunes of being rich today and poor tomorrow they may have something tangible to fall back upon. This provision might save many persons from misery, who by some unexpected turn of fortune have lost all their means.