Wisdom is not finally tested in schools, Wisdom cannot be pass'd from one having it to another not having it, Wisdom is of the soul, is not susceptible of proof, is its own proof, Applies to all stages and objects and qualities and is content, Is the certainty of the reality and immortality of things, and the excellence of things; Something there is in the float of the sight of things that provokes it out of the soul.

The Complete Writings of Walt Whitman: Leaves of grass (ed. 1902)