GIORDANO BRUNO AND GALILEO GALILEI. 



119 



" Galileo knew that all physical objects are ex- 

 tended, and consequently by their nature and es- 

 sence measurable, though they may not always be 

 measurable by the methods and instruments we 

 possess — that all physical phenomena take place 

 in periods susceptible of measure — that physical 

 phenomena must be reducible to movements, some 

 perceptible, others inappreciable by our senses. As 

 regarded all these phenomena, he held that the 

 right method was to measure all that was measura- 

 ble, and to endeavor to render measurable all that 

 was not already directly so. All who have pro- 

 ceeded a priori, from Aristotle to Descartes down- 

 ward, have arrived at results the falsity of which 

 suffices to condemn their method. Neither an- 

 cients, indeed, nor moderns, made any mistake 

 about the first principles of pure mathematics, 

 since those first principles, being necessary and 

 evident of themselves, have nothing to fear from 

 any correction in application. But those who have 

 sought to arrive at the first truths of mechanics by 

 the a priori instead of the inductive method have 

 always deceived themselves with regard to many 

 of those truths." 



In a letter addressed, but not sent, to the 

 Peripatetic professor Fortunio Liceti, dictated 

 by Galileo, at the age of seventy-seven, the year 

 before his death, he observed (and the observa- 

 tion comprises the whole substance of his own 

 scientific teaching) : 



" If the true philosophy were that which is con- 

 tained in the books of Aristotle, you would, in my 

 mind, be the first philosopher in the world, since 

 you seem to have every passage of that author at 

 your fingers' ends. But I verily think that the book 

 of philosophy is the book of Nature, a book which 

 always lies open before our eyes." 



The real cause of quarrel between Galileo and 

 the authorities of his age was, that the latter 

 sought their philosophy in books, while he sought 

 his in facts. A blind faith in Aristotle deprived 

 men of the use of their own eyes. Certain ultra- 

 Aristotelians went the length of affirming thit 

 Galileo's telescopes were so constructed as to 

 show things which in reality had no existence. 

 He offered a reward of 10,000 scudi to any one 

 who could make such clever glasses as those. 

 Some stubbornly refused to look through his tele- 

 scopes at all, assured as they were beforehand 

 that they never, by their aid, should see anything 

 that Aristotle had said a word about. And it 

 was not only a few Peripatetic philosophers, un- 

 versed in astronomy, who talked in this way. 

 Such language was repeated by the able astrono- 

 mer Magini, professor at Bologna, and at first, 

 also, by the learned Father Clavio, who died at 

 Home in 1610, but died converted to the faith 



(by sight) of Jupiter's satellites, the phases of 

 Venus, and the inequalities of the moon's sur- 

 face. Cremonini at Padua, and Libri at Pisa, 

 refused all credence to Galileo's discoveries, de- 

 monstrated as those discoveries were by his tele- 

 scopes. Libri died at Pisa without having ceased 

 to protest against Galileo's absurdities, or deigned 

 to look through Galileo's telescopes: upon which 

 the latter wrote (10th of December, 1610) that, as 

 the deceased professor would not look at Jupi- 

 ter's satellites here, he might, perhaps, take a 

 view of them in his way to heaven. 



It has often been asked — it was asked, indeed, 

 by Galileo himself — how it happened that a storm 

 of imputations of constructive heresy burst on his 

 head, after having left unvisited that of the first 

 great founder of modern astronomy, Copernicus. 

 Galileo could not, as he said, anticipate that it 

 would be believed at Rome — as it seemed to be 

 believed by Monsignor Gherardini, Bishop of 

 Fiesole — that the doctrine of the earth's motion 

 had been first started by a living Florentine, not 

 by a Polish canon who had been dead seventy 

 years, whose book had been published by special 

 desire of Cardinal Schomberg, and dedicated by 

 express permission to Pope Paul III. But it is 

 not difficult to discern the causes of the different 

 reception, by the reigning philosophical and ec- 

 clesiastical authorities at successive epochs, of 

 identically the same scientific truths. Coperni- 

 cus lay already paralyzed on his death-bed when 

 his work was intrusted to Osiander for publica- 

 tion, and he was therefore in no condition to 

 overrule the timid precautions which his above- 

 named pupil thought requisite in order to avert 

 the wrath of the orthodox theologians and Peri- 

 patetic philosophers of the day. Osiander's anon- 

 ymous preface in no manner expressed the mind 

 of his master, who was convinced as firmly, as 

 was afterward his illustrious Florentine succes- 

 sor, of the solid foundation of his system in the 

 facts of the natural universe, and who would 

 probably have been no more disposed than Gali- 

 leo was to handle it as a mere working hypothe- 

 sis, which need not be received as true, or even 

 probable, but as framed solely to facilitate th& 

 calculation of astronomical phenomena. Thc- 

 subterfuge was a childish one, but it passed mus- 

 ter with those childish minds of mature growth, 

 then occupying papal or professorial chairs and 

 pulpits. Had Copernicus lived to wield the 

 powers of Galileo's telescope, he, instead of Gali- 

 leo, might have stood forth the protagonist, and 

 have suffered as the protomartyr, of modern as- 

 tronomy. The conflict with the spiritual power, 



