Page:Early Greek philosophy by John Burnet, 3rd edition, 1920.djvu/164

150 into earth; in proportion as the sea is diminished by evaporation, it is fed by the earth. Lastly, the ignition of the bright vapour from the sea in the bowl of the sun completes the circle of the "upward and downward path."

72. How is it that, in spite of this constant flux, things appear relatively stable? The answer of Herakleitos was that it is owing to the observance of the "measures," in virtue of which the aggregate bulk of each form of matter in the long run remains the same, though its substance is constantly changing. Certain "measures" of the "ever-living fire" are always being kindled, while like "measures" are always going out (fr. 20). All things are "exchanged" for fire and fire for all things (fr. 22), and this implies that for everything it takes, fire will give as much. "The sun will not exceed his measures" (fr. 29).

And yet the "measures" are not absolutely fixed. We gather from the passage of Diogenes quoted above that Theophrastos spoke of an alternate preponderance of the bright and dark exhalations, and Aristotle speaks of Herakleitos as explaining all things by evaporation. In particular, the alternation of day and night, summer and winter, were accounted for in this way. Now, in a passage of the pseudo-Hippokratean treatise Περὶ διαίτης, which is almost certainly of Herakleitean origin, we read of an "advance of