when we burn anthracite or bituminous coal was also derived from the same source in the ultra-tropical climate of the secondary times, perhaps a thousand centuries ago. In such perpetually recurring cycles are the movements of material things accomplished, and all takes place under the dominion of invariable law. The air is the source whence all organisms have come; it is the receptacle to which they all return. Its parts are awakened into life, not by the influence of any terrestrial agency or principle concealed in itself, as Diogenes supposed, but by a star which is ninety millions of miles distant, the source, direct or indirect, of every terrestrial movement, and the dispenser of light and life. [Sidenote: Heraclitus asserts that fire is the first principle.] [Sidenote: The fictitious permanence of successive forms.] To Thales and Diogenes, whose primordial elements were water and air respectively, we must add Heraclitus of Ephesus, who maintained that the first principle is fire. He illustrated the tendency which Greek philosophy had already assumed of opposition to Polytheism and the idolatrous practices of the age. It is said that in his work, ethical, political, physical, and theological subjects were so confused, and so great was the difficulty of understanding his meaning, that he obtained the surname of "the Obscure." In this respect he has had among modern metaphysicians many successors. He founds his system, however, upon the simple axiom that "all is convertible into fire, and fire into all." Perhaps by the term fire he understood what is at present meant by heat, for he expressly says that he does not mean flame, but something merely dry and warm. He considered that this principle is in a state of perpetual activity, forming and absorbing every individual thing. He says, "All is, and is not; for though it does in truth come into being, yet it forthwith ceases to be." "No one has ever been twice on the same stream, for different waters are constantly flowing down. It dissipates its waters and gathers them again; it approaches and recedes, overflows and fails." And to teach us that we ourselves are changing and have changed, he says, "On the same stream we embark and embark not, we are and we are not." By such illustrations he implies that life is only an unceasing motion, and we cannot fail to remark that the Greek turn of thought is fast following that of the Hindu.