The dominant passion of an individual of the human species, when it disposes of the passions of many others, arrives at combining their will, at uniting their efforts, and thus decides the condition of man. It is after this manner that an ambitious, crafty, and voluptuous Arab, gave to his countrymen an impulse of which the effect was the subjugation and desolation of vast countries in Asia, in Africa, and in Europe; whose consequences were sufficiently potential to erect a new, extensive, but slavish empire; to give a novel system of religion to millions of human beings; to overturn the altars of their former gods; in short, to alter the opinions, to change the customs of a considerable portion of the population of the earth. But in examining the primitive sources of this strange revolution, what were the concealed causes that had an influence over this man--that excited his peculiar passions, and modified his temperament? What was the matter from the combination of which resulted a crafty, ambitious, enthusiastic, and eloquent man; in short, a personage competent to impose on his fellow-creatures--capable of making them concur in his most extravagant views. They were, undoubtedly, the insensible particles of his blood; the imperceptible texture of his fibres; the salts, more or less acrid, that stimulated his nerves; the proportion of igneous fluid that circulated in his system. From whence came these elements? It was from the womb of his mother; from the aliments which nourished him; from the climate in which he had his birth; from the ideas he received; from the air which he respired; without reckoning a thousand inappreciable, a thousand transitory causes, that in the instance given had modified, had determined the passions of this importent being, who had thereby acquired the capacity to change the face of this mundane sphere. To causes so weak in their principles, if in the origin the slightest obstacle had been opposed, these wonderful events, which have astounded man, would never have been produced. The fit of an ague, the consequence of bile a little too much inflamed, had sufficed, perhaps, to have rendered abortive all the vast projects, of the legislator of the Mussulmen. Spare diet, a glass of water, a sanguinary evacuation, would sometimes have been sufficient to have saved kingdoms.