Rethinking an important subject like the Scientific Revolution involves a complex process of recalibration and revaluation; topics which once seemed central become marginal, and topics which once seemed of merely antiquarian interest take on a new importance. There is a very extensive literature devoted to the relationship between Christianity and science in the early modern period.i Some argue that belief in a creator God was a fundamental prerequisite for modern science, as it made possible the idea of laws of nature, an idea unknown in ancient Greece and Rome, or in China. Others claim that there is a particular affinity between one or other particular sort of Christianity (Puritanism, for example) and the new science.ii I do not find these arguments convincing, although they are certainly intriguing. If monotheism was what counted, there would have been a scientific revolution in the Islamic and Orthodox worlds. If Protestantism was what counted, Galileo would not have been a great scientist. The idea of laws of nature represents a crucial test case, and theological questions do not prove to be fundamental: indeed, the key source for the concept appears to be Lucretius; and, as for the religious convictions of the first scientists, the only safe conclusion is that generalization is impossible. There are Jesuits and Jansenists, Calvinists and Lutherans, and some who have little or no belief. The first scientists appear, as far as their religious beliefs are concerned, to be a more or less random sample of the intellectuals of seventeenth-century Europe. Many of the scientists I have discussed were profoundly pious, but their religious faith was not what they had in common. To grasp this point one only has to think of Pascal and Newton, the first a Jansenist and the second an Arian.iii What they had in common was not religion but mathematics and, of course, a need for freedom of expression. ‘Me tenant comme je suis, un pied dans un pays et l’autre en un autre, je trouve ma condition très heureuse, en ce qu’elle est libre,’ wrote Descartes to Elizabeth of Bohemia in the summer of 1648 (‘Carrying on as I do, with one foot in one country [France] and the other in another [the Netherlands], I find my situation very happy, in that I am free.’