The interdependence of civilization is largely the result of man’s increasing _conquest of nature_; and this is the next contrast between civilized society and that of Africa. The difference between the canoe and the steamship is typical. Improved means of transportation, beginning with the use of steam, has made possible the exchange of products between remote countries. The ever-increasing knowledge of nature, resulting in mechanical inventions, has made near neighbours of the nations. We read the news of the world each morning. Money contributed in New York to-day for the relief of a famine in China is distributed there to-morrow. The whole world is embraced in our daily thought and interest. The African, unless he lives by a river, knows nothing of the world beyond the farthest village to which he has walked. Not even the invention of the wheel has reached him. The civilized man has made nature supplement himself; has made himself swifter than the swiftest of animals and stronger than the strongest, and has multiplied a thousandfold the product of his labour. In order to disseminate the benefits of this increasing conquest of nature there arises a demand for skilled labour; and upon the principle that a man can do but one thing in a lifetime and do it well, different classes appear, performing different functions in the social body, dependent upon one another as the various organs of the body depend upon one another, and society becomes an organism developing from simplicity to complexity. The _intellectual development_ of the civilized man as compared with the savage—his knowledge of the world in which he lives, and of man himself—his science and philosophy, his refining enjoyments of literature and music—all that is embraced in _education_ creates even a greater difference than that of material well-being. As steam and electricity have annihilated space so the printing-press has annihilated time. The knowledge and the wisdom of the past are recorded for our benefit. A pigmy standing on a giant’s shoulders (Macaulay observes) can see further than the giant; and a schoolboy of our times knows more astronomy than Galileo. Each generation stands upon the shoulders of the preceding generation. There is nothing in any way corresponding to this in Africa. There is no increase of knowledge and no expanding intelligence. The intellectual stagnation, the stifling mental torpor of an African community must be experienced in order to be realized.