I ON THE METHOD OF ZADIG 11 



of whose birth and death are uncertain, but who 

 flourished about 600 B.C., is said to have foretold 

 an eclipse of the sun which took place in his time 

 during a battle between the Medes and the 

 Lydians. Sir George Airy has written a very 

 learned and interesting memoir * in which he 

 proves that such an eclipse was visible in Lydia 

 on the afternoon of the 28th of May in the year 

 585 B.C. 



/f No one doubts that, on the day and at the 

 hour mentioned by the Astronomer-Royal, the 

 people of Lydia saw the face of the sun 

 totally obscured. But, though we implicitly be- 

 lieve this retrospective prophecy, it is incapable 

 of verification. In the total absence of historical 

 records, it is impossible even to conceive any 

 means of ascertaining directly whether the eclipse 

 of Thales happened or not. All that can be said 

 is, that the prospective prophecies of the astrono- 

 mer are always verified ; and that, inasmuch as 

 his retrospective prophecies are the result of 

 following backwards, the very same method as 

 that which invariably leads to verified results, 

 when it is worked forwards, there is as much 

 reason for placing full confidence in the one as in 

 the other. Retrospective prophecy is therefore a 

 legitimate function of astronomical science ; and 

 if it is legitimate for one science it is legitimate for 



1 "On the Eclipses of Agathocles, Thales, and Xerxes," 

 Philosophical Transactions, vol. cxliii. 



