This inflexibility of national peculiarities becomes invaluable in tracing the causes of the decay and disruption of the great Moslem empires which subsequently dominated so large a portion of the globe. The ethnography of a people who have stamped their characteristics deeply upon succeeding ages; whose customs, laws, and language have, to a certain degree, survived their dominion; the analogy between the religious dogmas which they professed and those which have supplanted them; the play of passions, destructive or beneficent, exhibited by those rulers whom hereditary descent or the accident of fortune raised to supreme authority; the development of the transplanted race, its precocious maturity, the lasting effects of its intellectual supremacy, and its slow but inevitable decline, are circumstances well deserving the attentive scrutiny of the philosophical historian. The absence of reliable information renders impossible an accurate conception of the mental and physical traits of the Arab of two thousand years ago. But, as we know the extreme conservatism of Orientals, their pronounced aversion to change, the obstinate persistence of their traditions, and the general outlines of their character, we may with safety assume that the shepherd who now roams over the desert plateaus of Nejd and Oman is the intellectual counterpart of the Amalekite of the Bible, and that the Arab whose features are sculptured upon the eternal walls of Edfou and Karnak did not differ in any material respect from the predatory Bedouin of to-day. It is a strange anomaly in a land, the greater portion of which, either through the obduracy of Nature or the indolence of its inhabitants, had been for ages condemned to eternal sterility and isolated by sea and desert from contemporaneous civilization, to encounter a race whose genius was capable of at once adapting itself, with equal facility, to the formation and development of an agricultural system surpassing that of any other people, ancient or modern; to the invention of mechanical devices of marvellous ingenuity; to the solution of the most abstruse mathematical problems; to the perfection of a graceful and exquisite order of architecture, unique in design, infinite in detail, remarkable in execution, unrivalled in beauty of ornament; to the protracted investment of cities and the attainment and exercise of that proficiency in the intricate system of military tactics indispensable to success in the art of war; to the foundation and the preservation of empires. A long and tedious apprenticeship is usually required for the attainment to perfection in any of these accomplishments; but the versatile Arab seemed, by intuition, to be able to grasp them all, without previous experience or instruction. In literature, as well, was this pre-eminence of genius disclosed. Poetry was the sole form of literary manifestation appreciated by the Arabic mind; improvisation the only talent it deemed worthy of applause.