 There is one final aspect of 17th century discussions of infinity that is relevant for later considerations: the problem of extending the concept of counting from the finite to the infinite. This problem is related to the issue of whether there is only one infinity or whether there might be different sizes of infinity. As we have mentioned, Philoponus argued that the eternity of the world led to a contradiction. In particular, he claimed, if the world has no beginning in the past, then the number of individuals up to Socrates would be infinite; but then by adding the number of individuals from Socrates to now, one would obtain an infinity larger than the previous one, and this, he concluded, is “one of the most impossible things” (see Sorabji 1983). It was typical of Greek thought to reject the idea that there can be different sizes of infinity.