d around the
Indian Sea. It has few gulfs, bays, capes, or islands. Even the rivers,
though large and long, are not means of communication with the outer
world, because from the central high plateau they plunge in rapids and
cataracts to the narrow coastlands and the sea.

The general physical contour of Africa has been likened to an inverted
plate with one or more rows of mountains at the edge and a low coastal
belt. In the south the central plateau is three thousand or more feet
above the sea, while in the north it is a little over one thousand feet.
Thus two main divisions of the continent are easily distinguished: the
broad northern rectangle, reaching down as far as the Gulf of Guinea and
Cape Guardafui, with seven million square miles; and the peninsula which
tapers toward the south, with five million square miles.

Four great rivers and many lesser streams water the continent. The
greatest is the Congo in the center, with its vast curving and endless
estuaries; then the Nile, draining the cluster of the Great Lakes and
flowing northward "like some grave, mighty thought, threading a dream";
the Niger in the northwest, watering the Sudan below the Sahara; and,
finally, the Zambesi, with its greater Niagara in the southeast. Even
these waters leave room for deserts both south and north, but the greater
ones are the three million square miles of sand wastes in the north.

More than any other land, Africa lies in the tropics, with a warm, dry
climate, save in the central Congo region, where rain at all seasons
brings tropical luxuriance. The flora is rich but not wide in variety,
including the gum acacia, ebony, several dye woods, the kola nut, and
probably tobacco and millet. To these many plants have been added in
historic times. The fauna is rich in mammals, and here, too, many from
other continents have been widely introduced and used.

Primarily Africa is the Land of the Blacks. The world has always been
familiar with black men, who represent one of the most ancient of human
stocks. Of the ancient world gathered about the Mediterranean, they formed
a part and were viewed with no surprise or dislike, because this world saw
them come and go and play their part with other men. Was Clitus the
brother-in-law of Alexander the Great less to be honored because he
happened to be black? Was Terence less famous? The medieval European
world, developing under the favorable physical conditions of the north
temperate zone, k