Order Directional Derivative

Famous quotes containing the words order and/or derivative:

    I don’t know but a book in a man’s brain is better off than a book bound in calf—at any rate it is safer from criticism. And taking a book off the brain, is akin to the ticklish & dangerous business of taking an old painting off a panel—you have to scrape off the whole brain in order to get at it with due safety—& even then, the painting may not be worth the trouble.
    Herman Melville (1819–1891)

    Poor John Field!—I trust he does not read this, unless he will improve by it,—thinking to live by some derivative old-country mode in this primitive new country.... With his horizon all his own, yet he a poor man, born to be poor, with his inherited Irish poverty or poor life, his Adam’s grandmother and boggy ways, not to rise in this world, he nor his posterity, till their wading webbed bog-trotting feet get talaria to their heels.
    Henry David Thoreau (1817–1862)