"The Eastern slaves, fulfilling my commands, wait for my summons where their eyes cannot see what we do. The danger is of a kind in which the boldest son of the East would be more craven, perhaps, than the daintiest Sybarite of Europe, who would shrink from a panther and laugh at a ghost. In the creed of the Dervish, and of all who adventure into that realm of nature which is closed to philosophy and open to magic, there are races in the magnitude of space unseen as animalcules in the world of a drop. For the tribes of the drop, science has its microscope. Of the host of yon azure Infinite magic gains sight, and through them gains command over fluid conductors that link all the parts of creation. Of these races, some are wholly indifferent to man, some benign to him, and some dreadly hostile. In all the regular and prescribed conditions of mortal being, this magic realm seems as blank and tenantless as yon vacant air. But when a seeker of powers beyond the rude functions by which man plies the clockwork that measures his hours, and stops when its chain reaches the end of its coil, strives to pass over those boundaries at which philosophy says, 'Knowledge ends,'--then he is like all other travellers in regions unknown; he must propitiate or brave the tribes that are hostile,--must depend for his life on the tribes that are friendly. Though your science discredits the alchemist's dogmas, your learning informs you that all alchemists were not ignorant impostors; yet those whose discoveries prove them to have been the nearest allies to your practical knowledge, ever hint in their mystical works at the reality of that realm which is open to magic,--ever hint that some means less familiar than furnace and bellows are essential to him who explores the elixir of life. He who once quaffs that elixir, obtains in his very veins the bright fluid by which he transmits the force of his will to agencies dormant in nature, to giants unseen in the space. And here, as he passes the boundary which divides his allotted and normal mortality from the regions and races that magic alone can explore, so, here, he breaks down the safeguard between himself and the tribes that are hostile. Is it not ever thus between man and man? Let a race the most gentle and timid and civilized dwell on one side a river or mountain, and another have home in the region beyond, each, if it pass not the intervening barrier, may with each live in peace. But if ambitious adventurers scale the mountain, or cross the river, with design to subdue and enslave the population they boldly invade, then all the invaded arise in wrath and defiance,--the neighbours are changed into foes. And therefore this process--by which a simple though rare material of nature is made to yield to a mortal the boon of a life which brings, with its glorious resistance to Time, desires and faculties to subject to its service beings that dwell in the earth and the air and the deep--has