VOLCANOES. 237 



mutter revolving elliptbahy in a gaseous condition. We have 

 thua mere conjecture and supposition side by side with cer- 

 tain knowledge. A philosophical study of nature strives ever 

 to elevate itself above the narrow requirements of mere natural 

 description, and does not consist, as we have already remark- 

 ed, in the mere accumulation of isolated facts. The inquir- 

 ing and active spirit of man must be suffered to pass from the 

 present to the past, to conjecture all that can not yet be known 

 with certainty, and still to dwell with pleasure on the ancient 

 myths of geognosy which are presented to us under so many 

 various forms. If we consider volcanoes as irregular inter- 

 mittent springs, emitting a fluid mixture of oxydized metals, 

 alkalies, and earths, flowing gently and calmy wherever they 

 find a passage, or being upheaved by the powerful expansive 

 force of vapors, we are involuntarily led to remember the geog- 

 uostic visions of Plato, according to which hot springs, as well 

 as all volcanic igneous streams, were eruptions that might be 

 traced back to one generally distributed subterranean cause, 

 Pyriphlcgcthon* 



/ * According to Plato's geognostic views, as developed in the Phtedo, 

 Pyriphlegelhon plays much the same part in relation to the activity of 

 volcanoes that we now ascribe to the augmentation of heat as we de- 

 scend from the earth's surface, and to the fused condition of its internal 

 strata. (Pheedo, ed. Ast, p. 603 and 607; Aunot., p. 808 and 817.) 

 " Within the earth, aud all around it, are larger and smaller caverns. 

 \V r ater flows there in abundance ; also much tire 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 erup- 

 tion. 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 

 und 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 Pyri- 

 phlegethon constituted, from which also the streams of fire (oi fivanes), 

 wherever they reach the earth (OTTIJ uv rv^uai rr;f y?f), inflate such 

 parts (detached fragments)." Volcanic scoria} and lava streams are 

 therefore portions of Pyriphlegethon itself, portions of the subterranean 

 molten and ever-undulating mass. That oi /iua/cef are lava streams, and 

 not, as Schneider, Passow, and Schleiermacher will have it, " fire-vom- 

 iting mountains," is clear enough from many passages, some of which 

 have been collected by Ukert (Gcogr. der Oriechen und Rumer, th. ii., 

 s. 200) ; fivai; is the volcanic phenomenon in reference to its most strik- 

 ing characteristic, the lava stream. Hence the expression, the ftvaxcf 

 of ./Etna. 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 placet 

 near the sea, in the neighborhood of ^Etna, were leveled to the ground 

 vrrd TOV KdAovpevov j>i>a>ior ;" St-jb<, vi., p. 2C9; xiii., p. 2(18, aud 



