222 CLASSICS OF MODERN SCIENCE 

 tion and subterranean movement, accompanied by a constant dying- 

 out and renovation of species. 



As all the conclusions above insisted on are directly opposed to 

 opinions still popular, I shall add another comparison, in the hope of 

 preventing any possible misapprehension of the argument. Suppose 

 we had discovered two buried cities at the foot of Vesuvius, immedi- 

 ately superimposed upon each other, with a great mass of tuflf and 

 lava intervening, just as Portici and Resina, if now covered with 

 ashes, would overlie Herculaneum. An antiquary might possibly be 

 entitled to infer, from the inscriptions on public edifices, that the in- 

 habitants of the inferior and older city were Greeks, and those of the 

 modern town Italians. But he would reason very hastily if he also 

 concluded from these data, that there had been a sudden change from 

 the Greek to the Italian language in Campania. But if he afterwards 

 found three buried cities, one above the other, the intermediate one 

 being Roman, while, as in the former example, the lowest was Greek 

 and the uppermost Italian, he would then perceive the fallacy of his 

 former opinion and would begin to suspect that the catastrophes, 

 by which the cities were inhumed, might have no relation whatever 

 to the fluctuations in the language of the inhabitants; and that, as 

 the Roman tongue had evidently intervened between the Greek and 

 Italian, so many ether dialects may have been spoken in succession, 

 and the passage from the Greek to the Italian may have been very 

 gradual, some terms growing obsolete, while others were introduced 

 from time to time. 



If this antiquary could have shown that the volcanic paroxysms of 

 Vesuvius were so governed as that cities should be buried one above 

 the other, just as often as any variation occurred in the language of 

 the inhabitants, then, indeed, the abrupt passage from a Greek to a 

 Roman, and from a Roman to an Italian city, would afford proof of 

 fluctuations no less sudden in the language of the people. 



So, in Geology, if we could assume that it is part of the plan of 

 Nature to preserve, in every region of the globe, an unbroken series of 

 monuments to commemorate the vicissitudes of the organic creation, 

 we might infer the sudden extirpation of species, and the simultaneous 

 introduction of others, as often as two formations in contact are found 

 to include dissimilar organic fossils. But we must shut our eyes 

 to the whole economy of the existing causes, aqueous, igneous, and 



