DE FLUXU ET REFLUXU MARIS. 245 



to determine experimentally which of the two theo 

 ries he has mentioned is the true one ; as only angels 

 could make observations on both sides of the ocean at 

 once, the eyes of men not reaching far enough to do 

 so, and the distance being too great to be crossed by 

 man in the time of a single tide. 



