218 THE ESSENCE OF HUMANITY. 



and habitation develope under the influence of man's rational 

 consciousness into all those manifold arts by means of which 

 he is clothed, housed, warmed, lighted, and provided with all 

 those co-ordinated social and civic arrangements which result 

 in the economics of the house, hamlet, farm, city, and state. 

 The latter arrangements compel man, collected in masses, to 

 develope for himself, on instinctive and scientific grounds, the 

 sanitary regulations which such circumstances force upon his 

 attention. But even in our present so-called civilized condi- 

 tion, man shows himself in many respects behind the animal 

 in his sanitary arrangements and precautions. The animal 

 never disobeys, if left to the guidance of its own instincts, the 

 physiological laws of its economy. It is a perfect sanitarian. 

 Our present so-called civilization has only reached the phase 

 of sanitary reform. 



11. But man, like the animal, not only finds his subsistence 

 in his geographical area, but also reacts upon it. Here, again, 

 we find that the purposes served by the animal are to a great 

 extent secondary in importance. It merely co-operates in 

 that series of phyto-zoological, or organic actions, which, along 

 with the cotemporaneous cosmical or inorganic processes, 

 tend at any time to prepare the surface of the globe for the 

 reception of man, or maintain it in a condition fitted for his 

 economy. The changes effected by human agency on the sur- 

 face are of a much more positive kind. The clearing of 

 forests, the recovery of dry surface by coast and river embank- 

 ment, and by draining, the securing of moisture by irrigation, 

 are processes which not only prepare the surface for agricul- 

 tural produce, but induce at the same time an appropriate 

 change of climate. The changes of surface and climate, 

 induced by human agency, tend to check the productivity of 

 certain vegetable and animal forms ; or by entirely removing 

 their proper conditions of life, cause the local or general dis- 

 appearance of others. The formation of roads, of bridges, of 



