[footnote] *According to Plato's geognostic views, as developed in the 'Phaedo', Pyriphlegethon plays much the same part in relation to the activity of volcanoes that we now ascribe to the augmentation of heat as we descend from the earth's surface, and to the fused condition of its internal strata. ('Phaedo', ed. Ast, p. 603 and 607; Annot., p. 308 and 817.) "Within the earth, and all around it, are larger and smaller caverns. Water flows there in abundance; also much fire and large streams of fire, and streams of moist mud (some purer and others more filthy), like those in Sicily, consisting of mud and fire, preceding the great eruption. These streams fill all places that fall in the way of their course. Pyriphlegethon flows forth into an extensive district burning with a fierce fire, where it forms a lake larger than our sea, boiling with water and mud. From thence it moves in circles round the earth, turbid and muddy." This stream of molten earth and mud is so much the general cause of volcanic phenomena, that Plato expressly adds, "thus is Pyriphlegethon constituted, from which also the streams of fire ([Greek words]), wherever they reach the earth ([Greek words]), inflate such parts (detached fragments)." Volcanic scoriae and lava streams are therefore portions of Pyriphlegethon itself, portions of the subterranean molten and ever-undulating mass. That {Greek words] are lava streams, and not, as Schneider, Passow, and Schleiermacher will have it, "fire-vomiting mountains," is clear enough from many passages, some of which have been collected by Ukert ('Geogr. der Griechen und Romer', th. ii., s. 200): [Greek word] is the volcanic phenomenon in reference to its most striking characteristic, the lava stream. Hence the expression, the [Greek word] of Aetna. Aristot. 'Mirab. Ausc.', t. ii., p. 833; sect. 38, Bekker; Thucyd., iii., 116; Theophrast., 'De Lap'., 22, p. 427, Schneider; Diod., v., 6, and xiv., 59, where are the remarkable words, "Many places near the sea, in the neighborhood of Aetna, were leveled to the ground, [Greek words];" Strabo, vi., p. 269; xiii., p. 268, and where there is a notice of the celebrated burning mud of the Lelantine plains, in Euboea, i., p. 58, Casaub.; and Appian, 'De Bello Civili', v., 114. The blame which Aristotle throws on the geognostical fantasies of the Phaedo ('Meteor.', ii., 2, 19) is especially applied to the sources of the rivers flowing over the earth's surface. The distinct statement of Plato, that "in Sicily eruptions of wet mud precede the glowing (lava) stream," is very remarkable. Observations on Aetna could not have led to such a statement, unless pumice and ashes, formed into a mud-like mass by admixture with melted snow and water, during the volcano-electric storm in the crater of eruption, were mistaken for ejected mud. It is more probable that Plato's streams of moist mud ([Greek words]) originated in a faint recollection of the salses (mud