he says that the Galaxy is no other than a multitude of fixed stars in that part, so small that we cannot distinguish them from here below, but that they cause the whiteness which we call the Milky Way.  And it may be that the Heaven in that part is more dense, and therefore retains and represents that light; and this opinion Avicenna and Ptolemy seem to share with Aristotle.  Therefore, since the Galaxy is an effect of those stars which we cannot see, if we understand those things by their effect alone, and Metaphysics treats of the first substances, which we cannot similarly understand except by their effects, it is evident that the Starry Heaven has a great similitude to Metaphysics.

Again, by the pole which we see is signified the things known to our senses, concerning which, taking them universally, the Science of Physics treats; and by the pole which we do not see is signified the things which are without matter, which are not sensible, concerning which Metaphysics treats; and therefore the said Heaven has a great similitude with the one Science and with the other.

Again, by the two movements it signifies these two Sciences:  for by the movement in which every day revolves, and makes a new revolution from point to point, it signifies things natural and corruptible which daily complete their path, and their material is changed from form to form; and of this the Science of Physics treats.  And by the almost insensible movement which it makes from West to East by one degree in a hundred years, it signifies things incorruptible, which received from God the beginning of their creation, and will have no end; but of these Metaphysics treats.  Therefore I say that this movement signifies those things, for it began this revolution which will have no end; the end of the revolution being to return to one self-same point, to which this Heaven will not return by this movement, which has revolved a little more than the sixth part from the commencement of the world; and we are now in the last age of the world, and verily we wait the consummation of the celestial movement.  Thus it is evident that the Starry Heaven, on account of many properties, may be compared to the Science of Physics and Metaphysics.

The Crystalline Heaven, which, as the Primum Mobile, has been previously counted, has a sufficiently evident comparison to Moral Philosophy; for Moral Philosophy, according to what Tommaso says upon the second book of the Ethics, teaches us method in the other Sciences.

For as the Philosopher says in the fifth book of the Ethics, legal Justice requires the Sciences to be learnt, and commands, in order that they may not be abandoned, that they be learnt and taught:  thus, the said Heaven rules with its movement the daily revolution of all the others; from which revolution every day all those receive and send below the virtues of their several parts.  For, if the revolution of this Heaven could not rule over that, but little of their