1^8 Science Religion and Reality 



generally every other error and heresy contrary to the said Holy 

 Church, and I swear that I will never more in future say, or assert 

 anything, verbally or in writing, which may give rise to a similar 

 suspicion of me ; and that if I shall know any heretic or any one 

 suspected of heresy, I will denounce him to this Holy Office, or to 

 the Inquisitor and Ordinary of the place in which I may be. I 

 swear, moreover, and promise that I will fulfil and observe fully all 

 the penances which have been or shall be laid on me by this Holy 

 Office. But if it shall happen that I violate any of my said 

 promises, oaths, and protestations (which God avert), I subject 

 myself to all the pains and punishments which have been decreed 

 and promulgated by the sacred canons and other general and par- 

 ticular constitutions against delinquents of this description. So, 

 may God help me, and these His Holy Gospels which I touch with 

 my own hands." 



In character and temper Johannes Kepler (i 571-1630) was 

 almost as much a contrast to Galileo as was Copernicus to Vesalius 

 in the previous century. Kepler, a German, a mystic and dreamer, 

 essentially a mathematician rather than an experimenter, produced 

 voluminous works that are now almost unreadable. He stands over 

 against Galileo, the Italian, with his clear cold intellect, his un- 

 rivalled experimental skill, his wit and his great artistic and literary 

 prowess. In sheer genius, however, the two men were not rivals 

 but peers and comrades. On them in equal measure rest the 

 foundations of the great physical synthesis. 



Kepler's idea of the universe was from the first essentially 

 Platonic, or perhaps we should say Pythagorean. He was con- 

 vinced that the arrangement of the world and its parts must corre- 

 spond with certain abstract conceptions of the beautiful and the 

 harmonious. It was this faith that sustained him in his vast and 

 almost incredible labours. In estimating those labours the reader 

 may be reminded that he spent years of his life chained to the mere 

 drudgery of computation, without any outside assistance and with- 

 out any of the devices such as mechanical computers or the use of 

 logarithms that lighten the task of the modern worker. Nothing 

 but a burning faith could have made such drudgery possible. 



We gain an insight into the transition state between the old 

 and the new in which Kepler worked when we recall that his pro- 

 fessed occupation was largely astrological calculation. Nor was 

 he cynically sceptical as to the claims of astrology as were some of 



