Maxims are to the intellect what laws are to actions; they do not enlighten, but they guide and direct; and although themselves blind, are protective. They are like the clue in the labyrinth, or the compass in the night.

Joseph Joubert (1754-1824) French moralist, philosopher, essayist, poet

Pensées, # 138 (1838)
    (Source)

Alt. trans.: "Maxims are to the intelligence what laws are to action: they do not illuminate, but they guide, they control, they rescue blindly. They are the clue in the labyrinth, the ship's compass in the night."