I907.] AND CONTRACTION OF THE EARTH. 297 



somewhat vague language of Diodorus Siculus, who says that the 

 sea wave occurred in the day following the earthquake at night. 

 None of these accounts are to be too implicitly trusted, because 

 Pausanias says no one at Helike escaped, while Diodorus implies 

 that some persons were escaping when the wave overwhelmed the 

 city. 



If there had been a series of slight but incessant earthquake 

 shocks previous to the terrible earthquake at night, the account given 

 by ^lianus of the exodus of mice, weasels, and other animals from 

 the town becomes very intelligible; but here again we must beware 

 of reposing too much confidence in narratives composed after the 

 lapse of several centuries. Of all the contemporaries of this event, 

 Aristotle was best qualified to speak with authority ; but, as we have 

 seen, his account gives only the leading facts without the details 

 added by later writers, and is impossible to estimate how many of 

 these details are authentic. 



On the whole it appears to be certain that there were many 

 premonitory signs of the disaster, in the form of a series of prelimi- 

 nary shocks extending through several months and felt all over the 

 Peloponnesus; and it seems equally certain that the greatest shock 

 occurred in the night. This leveled Helike and Bura to the ground, 

 and was due to the expulsion from beneath the bed of the sea of a 

 mass of lava which was pushed under the mountains in Arcadia, 

 causing great chasms to open near Bura. In consequence of this 

 undermining of the sea bottom it afterwards gave down nearly a 

 hundred feet, but we cannot be sure whether the subsidence took 

 place with the great shock in the night, or followed from one of the 

 violent aftershocks the next day. On the whole the latter view seems 

 the most probable, since there is no reason why the sea bottom once 

 undermined might not sink with one of the violent after shocks which 

 always follow great earthquakes. 



When we consider the interval of time by which we are removed 

 from this great disaster, it is quite remarkable that our knowledge 

 of it should be so complete as it is. Plato was then in his fifty-fourth 

 year, at the height of his powers, and at the head of the Academy 

 in Athens, and Aristotle was a boy eleven years old ; but the im- 

 pression made upon contemporary Greek thought was proportionate 



