Such do not know that like the seed is the fruit, and that, in the moral world, when good seed is planted, good fruit is inevitable, and does not depend on our watering and cultivating; that when you plant, or bury, a hero in his field, a crop of heroes is sure to spring up. This is a seed of such force and vitality, that it does not ask our leave to germinate.

Henry David Thoreau (1817-1862) American philosopher and writer

Speech (1859-10-30), “A Plea for Captain John Brown,” Concord, Massachusetts
    (Source)

Collected in A Yankee in Canada (1866).