A human life is too short for the acquisition by oneself of the wisdom needed to live it well -- or to end it well. And the same goes for the appropriation of the hard-won wisdom of one's predecessors: the brevity of life militates against the needed appropriation as much as against the needed acquisition. So wisdom must come from outside the human-all-too-human if it is to come at all.
Addendum . Dave Bagwill submits the following pertinent quotation from George MacDonald's Diary of an Old Soul for July 15th:
Who sets himself not sternly to be good, Is but a fool, who judgment of true things Has none, however oft the claim renewed. And he who thinks, in his great plenitude, To right himself, and set his spirit free, Without the might of higher communings, Is foolish also--save he willed himself to be.