ages before what is commonly called the beginning of the historic period it would be simply logical, considering many national destructions which have occurred during the historic period, to conclude by analogy that races of remote antiquity flourished and passed away leaving no sign, which has been yet discovered, of their power and civilization. It is evident the historian Macaulay thinks it not improbable such may be the fate of England, and he expressly states in a well-known passage that the time may come when only a single naked fisherman may be seen in the river of the ten thousand masts. It is difficult, if not impossible, for mankind entirely to overcome the tendency to decay. [Illustration: ARAB SLAVE TRADERS.] We shall presently see that Africa is a field upon which must soon be decided a great issue of politico-social importance; an issue which involves the abolition of polygamy, domestic slavery, and the suppression of the foreign slave trade. From what has gone before in this volume, it will have been seen that here, too, are likely to be most conclusively demonstrated the vast age of the world, the great antiquity of man, and the nature of his origin. In comparison of the settlement of this issue and the solution of these problems of science, even the discovery of the true sources of the Nile may be regarded as unimportant, except for the reason that Dr. Livingstone’s great achievement will arouse other men of science to similar sacrifices, labors, and fortitude. Thus Africa is found to present another remarkable contrast for our contemplation; for while civilization is there at a lower ebb than in any other grand division of the globe, the highest intellectual efforts of the most astute thinkers of the times are turning their best efforts thitherward, in the confident hope of greatly enlarging the sphere of human knowledge, and of extending the triumphs of science and civilization.