And of this there is a good and sufficient testimony in the very colour of that same people of Ethiopia, whose blood is burnt by the great heat of the sun, which there hath the full power of its heat, and the breath of the south-west wind,[BH] which is the hottest of all winds; whence the men of that land have their colour exceeding black; and moreover, no river, whatever it be, that swelleth for reason of the snow or ice that hath recourse to it, is augmented except from the time of the entry of the summer season; for then the snow and ice begin to melt by reason of the heat; but the Nile doth not raise its waters so high, nor do they swell in its bed before the rising of that same Dog Star, nor do its waters reach outwards to their banks until the day is equal to the night, which is in the month of September, when the sun entereth into the sign of Libra. From all which it appeareth clearly that the Nile doth not follow the rule of any other waters; but when the sky becometh distempered in the midst of the great heat of the sun, the Nile issueth forth with the swelling of its waters, and this is under the belt of the mid-day, which is scorching hot. [Footnote BH: Aurego.] And this it doth that the flame of the axis of the firmament, by reason of its increase, may not set fire to the land and burn it. And so the Nile is as it were a succour to the world, because when the mouth of Leo is kindled, and when Cancer burneth over its city of Syene in Egypt, then riseth this river against the mouths of the twain, to temper their fire, the which is a matter of the utmost need to the peoples of the earth.