It may seem paradoxical to maintain that by cultivation we at times render the earth insalubrious, at times comparatively the reverse, but the fact is so. It was Humboldt, as I have already remarked, who said that when Europeans first emigrated to America, the soil of certain northern states was found equal to the growth of wheat, and ague afflicted the population. With the destruction of the forests, the agues have disappeared, and wheat can no longer be grown; in the place of agues men are now afflicted with pulmonary consumption. Whoever has seen the marshy and boggy land, at times a lake, at others a black tremulous morass, and compared it with the rich drained Polder, its neat and compact farm-house, exhaustless meadows, herds of cattle, and the contented air of its well-to-do proprietor, will at once perceive that whatever might be the evil, unless it were a something truly grievous, so delightful a metamorphosis of a spot doomed by nature to eternal sterility, entailed on man, that evil was fully compensated for by the results obtained towards man’s happiness. There is, there can be, or at least there never was, any unmixed good on earth: the whole is a system of comparison and compensation; of profit or loss; of gains and drawbacks. When the English army died off at Walcheren the inhabitants of the province were perfectly healthy, and could not comprehend the cause of the calamity. It was the same in the Crimea. Under other arrangements, those more consonant with common sense and experience, the results might have been different; still it is certain that masses of young men of immature years cannot be withdrawn from their native soil and parents’ hearths without suffering severely the consequence of the every way unnatural position they are forced to occupy; unnatural physically and morally. Barrack-rooms are not homes. No varied society is to be found there; no amusement, no employment for mind and body; it is man cut off from all human industry and enjoyment; no solace when ill, no comfort under suffering: that young men with unformed constitutions should “die off like flies,”[41] need excite no surprise. [41] The expression of Lord Raglan when he demanded from England veteran troops, and not lads of immature age, to be sent to the seat of war. To return: to modern science, above all to Liebig, the practical chemist _par excellence_, we owe the discovery of the true office of _ulmine_ or _humus_ in vegetation; it nourishes the plant before it is in a position to draw its nourishment from the atmosphere. The vegetation called antediluvian had this peculiar character, that it enabled the plant to be greatly independent of roots and soil; its broad-leaved foliage sought everywhere for food in the carbonic acid of the atmosphere. Accordingly all the plants were remarkable for the smallness of their roots, which generally have disappeared, and are now no longer to be found.