Page:In defense of Harriet Shelley, and other essays.djvu/410

 MARK TWAIN

necessary to attain it a labor compared with which the efforts needed to acquire the degree of Doctor of Philosophy at a university are as light as a summer course of modern novels. To appreciate the full meaning of a pilot s marvelous education, one must read the whole of Life on the Mississippi, but this extract may give a partial idea of a single feature of that training the cultivation of the memory:

&quot;First of all, there is one faculty which a pilot must incessantly cultivate until he has brought it to absolute perfection. Nothing short of perfection will do. That faculty is memory. He cannot stop with merely thinking a thing is so and so; he must know it; for this is eminently one of the exact sciences. With what scorn a pilot was looked upon, in the old times, if he ever ventured to deal in that feeble phrase I think/ instead of the vigorous one I know ! One cannot easily realize what a tre mendous thing it is to know every trivial detail of twelve hundred miles of river, and know it with absolute exactness. If you will take the longest street in New York, and travel up and down it, conning its features patiently until you know every house, and window, and door, and lamp-post, and big and little sign by heart, and know them so accurately that you can instantly name the one you are abreast of when you are set down at random in that street in the middle of an inky black night, you will then have a tolerable notion of the amount and the exactness of a pilot s knowledge who carries the Mississippi River in his head. And then, if you will go on until you know every street-crossing, the

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