Gold and silver had been fixed upon in India as proper returns for their manufactures and produce. It is impossible to say whether it was from their hardness or beauty, or what other reason governed the mind of man in making this standard of barter. The history of the particular transactions of those times is lost, if, indeed, there ever was such history, and, therefore, all further inquiries are in vain. The choice, it seems, was a proper one, since it has continued unaltered so many ages in India, and has been universally adopted by all nations pretty much in the proportion or value as in India, into which continent gold and silver, from this very early period, began to flow, have continued so to do to this day, and in all probability will do to the end of time. What has become of that immense quantity of bullion, how it is consumed, or where it is deposited, and which way, if ever it returns, are doubts which I never yet found a person that could satisfactorily solve. The Cushite then inhabited the mountains, whilst the northern colonies advanced from Meroë to Thebes, busy and intent upon the improvement of architecture, and building of towns, which they began to substitute for their caves; they thus became traders, farmers, artificers of all kinds, and even practical astronomers, from having a meridian night and day free from clouds, for such was that of the Thebaid. As this was impossible to their brethren, and six months continual rain confined them to these caves, we cannot doubt but that their sedentary life made them useful in reducing the many observations daily made by those of their countrymen who lived under a purer sky. Letters too, at least one sort of them, and arithmetical characters, we are told, were invented by this middle part of the Cushites, while trade and astronomy, the natural history of the winds and seasons, were what necessarily employed the part of the colony established at Sofala most to the southward. The very nature of the Cushites commerce, the collecting of gold, the gathering and preparing his spices, necessarily fixed him perpetually at home; but his profit lay in the dispersing of these spices through the continent, otherwise his mines, and the trade produced by the possession of them, were to him of little avail.