Brown's and Darwin's theories are both ingenious; but the first will not account for sleep, and the last will not account for death: considerable defects, you must allow.
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It is said that every excitation is followed by a commensurate exhaustion. That is not so. The excitation caused by inhaling nitrous oxide is an exception at least; it leaves no exhaustion on the bursting of the bubble. The operation of this gas is to prevent the decarbonating of the blood; and, consequently, if taken excessively, it would produce apoplexy. The blood becomes black as ink. The voluptuous sensation attending the inhalation is produced by the compression and resistance.
May 2. 1830.
PLANTS.—INSECTS.—MEN.—DOG.—ANT AND BEE.
Plants exist in themselves. Insects by, or by means of, themselves. Men, for themselves. The perfection of irrational animals is that which is best for them; the perfection of man is that which is absolutely best. There is growth only in plants; but there is irritability, or, a better word, instinctivity, in insects.
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You may understand by insect, life in sections—diffused generally over all the parts.
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The dog alone, of all brute animals, has a [*Greek: storgae], or affection upwards to man.