To teach is to learn twice.
This concern with the basic condition of freedom -- the absence of physical constraint -- is unquestionably necessary, but is not all that is necessary. It is perfectly possible for a man to be out of prison and yet not free -- to be under no physical constraint and yet to be a psychological captive, compelled to think, feel and act as the representatives of the national State, or of some private interest within the nation, want him to think, feel and act.
Oh! if, when we oppress and grind our fellow-creatures, we bestowed but one thought on the dark evidences of human error, which, like dense and heavy clouds, are rising, slowly it is true, but not less surely, to Heaven, to pour their after-vengeance on our heads; if we heard but one instant, in imagination, the deep testimony of the dead men's voices, which no power can stifle, and no pride shut out; where would be the injury and injustice: the suffering, misery, cruelty, and wrong: that each day's life brings with it!
Humor is not a postscript or an incidental afterthought; it is a serious and weighty part of the world's economy. One feels increasingly the height of the faculty in which it arises, the nobility of things associated with it, and the greatness of services it renders.