Of all those that have written upon these countries, the prophet Isaiah alone has given an account of this animal, and the manner of its operation. Isa. vii. ch. 18. and 19. ver. “And it shall come to pass, in that day, that the Lord shall _hiss_ for the fly that is in the uttermost part of the rivers of Egypt,”--“And they shall come, and shall rest all of them in the desolate vallies[227], and in the holes of the rocks, and upon all thorns, and upon all bushes.” The mountains that I have already spoken of, as running through the country of the Shepherds, divide the seasons by a line drawn along their summit, so exactly, that, while the eastern side, towards the Red Sea, is deluged with rain for the six months that constitute our _winter_ in Europe, the western side toward Atbara enjoys a perpetual sun, and active vegetation. Again, the six months, when it is our _summer_ in Europe, Atbara, or the western side of these mountains, is constantly covered with clouds and rain, while, for the same time, the shepherd on the eastern side, towards the Red Sea, feeds his flocks in the most exuberant foliage and luxuriant verdure, enjoying the fair weather, free from the fly or any other molestation. These great advantages have very naturally occasioned these countries of Atbara and Beja to be the principal residence of the shepherd and his cattle, and have entailed upon him the necessity of a perpetual change of places. Yet so little is this inconvenience, so short the peregrination, that, from the rain on the west side, a man, in the space of four hours, will change to the opposite season, and find himself in sun-shine to the eastward. When Carthage was built, the carriage of this commercial city fell into the hands of Lehabim, or Lubim, the Libyan peasants, and became a great accession to the trade, power, and number of the shepherds. In countries to which there was no access by shipping, the end of navigation was nearly answered by the immense increase of camels; and this trade, we find, was carried on in the very earliest ages on the Arabian side, by the Ishmaelite merchants trading to Palestine and Syria, from the south end of the peninsula, with camels. This we learn particularly from Genesis, they brought myrrh and spices, or pepper, and sold them for silver; they had also balm, or balsam, but this it seems, in those days, they brought from Gilead.