PHYSICS intellect and will were purely bodily faculties, then the stars would indeed be able to act on them directly; but since these faculties are spiritual, they escape their fatal inXuence To those who claim that astrologers are successful in predicting the outcome of wars, Aquinas replies that this is because the majority of humans fail to exercise their free will and yield instead to their bodily passions Hence astrologers can make statistically reliable predictions, but they cannot foretell the fate of an individual Astrologers themselves admit, he says, that the wise man can overcome the stars (1a 115 4) Actual and Potential InWnity Most medieval philosophers accepted the position of Aristotle that the notion of an actually inWnite number was incoherent Matter, he maintained, was divisible to inWnity: but this meant, not that matter had inWnitely many parts, but that however often it had been divided it could always be divided further The inWnite, he maintained, had only a potential existence Aristotle himself objected only to a synchronic actual inWnite The universe, he believed, had existed for ever, and that must mean that an inWnite number of periods of time had already passed However, his theorem was applied by medieval philosophers not only to the divisibility of the continuum, but also to the duration of the created universe Those who wished to prove that the world had been created in time often argued that belief in an eternal universe entailed belief in an actual inWnite Thus Bonaventure argues as follows: It is impossible for any addition to be made to what is inWnite This is clear, because whatever is added to becomes greater, but nothing is greater than the inWnite But if the world had no beginning, it has lasted for inWnity; therefore, no addition can be made to its duration But it is clear that this is false; every day a new solar revolution is added to all the past revolutions Perhaps you will say that it is inWnite with respect to the past, but actually Wnite with respect to the present that now obtains, and it is only with respect to the current, Wnite, part that one can Wnd something greater But we can show that with respect to the past a greater can be found It is an unquestionable truth that if the world is eternal, there have been inWnite revolutions of the sun, and moreover that there have been twelve 185