390 HISTORY OF FORMAL ASTRONOMY. 



ledge. He must have seen, with peculiar distinct- 

 ness, the consequences which flowed from his sup- 

 positions as to the relations of space and time, the 

 apparent motions which resulted from the assumed 

 real ones; and he must also have known well all 

 the irregularities of the apparent motions for which 

 he had to account. We find indications of these 

 qualities in his expressions. A steady and calm 

 contemplation of the theory is what he asks for, as 

 the main requisite to its reception. If you suppose 

 the earth to revolve and the heaven to be at rest, 

 you will find, he says, "si serio animadvertas" if 

 you think steadily, that the apparent diurnal motion 

 will follow. And after alleging his reasons for his 

 system, he says 1 , "We are, therefore, not ashamed 

 to confess, that the whole of the space within the 

 orbit of the moon, along with the center of the 

 earth, moves round the sun in a year among the 

 other planets ; the magnitude of the world being so 

 great, that the distance of the earth from the sun 

 has no apparent magnitude when compared with 

 the sphere of the fixed stars." " All which things, 

 though they be difficult and almost inconceivable, 

 and against the opinion of the majority, yet, in the 

 sequel, by God's favour, we will make clearer than 

 the sun, at least to those who are not ignorant 

 of mathematics." 



It will easily be understood, that since the ancient 



1 Nicolai Copernici Torinensis de Revolutionibus Orbium 

 Ccelestium. Norimbergae. M.D.XLIII. p. 9. 



