GALILEO AND HIS JUDGES. 57 



bered that a dialogue, though a convenient form of 

 argument in some respects, does not always give one 

 a clear insight into the author's real convictions. 

 You are not sure whether he quite agrees with any of 

 the spokesmen, and, indeed, Galileo, in his defence 

 before the Inquisition, practically assumes that he 

 did not so agree. It is, however, a good form of 

 discussion for a man whose opinions are intended to 

 be expressed in a tentative shape, and perhaps Galileo's 

 mind was in a state congenial to such expression. 

 But, at any rate, it makes it rather more difficult 

 to do justice to the" author, as oue is never sure 

 what he intends to be taken as the expression of 

 his own deliberate belief; indeed, whatever may have 

 been the amount of indecision in which in this case 

 our author's mind was involved, it is scarcely possible, 

 notwithstanding his disclaimer, to ignore the fact of 

 his strong Copernican opinions. 



I think one may say that Galileo did not, at the 

 time when he wrote the dialogue, know the gravity of 

 the air. I say at that time, because it is quite 

 possible that he knew it before his death, since he 

 lived some ten or twelve years after writing this 

 work. It is maintained that he knew it because 

 there is extant a letter from Baliani, the date of 

 which I believe to be about 1631, in which the latter 

 expresses his acknowledgments to Galileo for having 

 taught him this truth. May it not, however, be that 

 what is here meant is the pressure of the air ? If 

 any one thinks Galileo understood at that time the 



