I say that the Starry Heaven may be compared to Physics because of three properties, and to Metaphysics because of three others. For it shows us of itself two visible things, such as the multitude of stars and such as the Galaxy, that white circle which the common people call the Path of St. James. It shows to us also one of the poles, and keeps the other hidden from us. And it shows to us one movement alone from East to West; and another, which it makes from West to East, it keeps almost, as it were, hidden from us. Therefore, in due order are to be seen, first the comparison with the Physical and then that with the Metaphysical. I say that the Starry Heaven shows us many stars; for, according to what the wise men of Egypt have seen, even to the last star which appeared to them in the Meridian, they place there twenty-two thousand bodies of stars, of which I speak. And in this it has the greatest similitude with Physics, if these three numbers, namely, Two, and Twenty, and Thousand, are regarded well and subtly. For by the two is meant the local movement, which is of necessity from one point to another; and by the twenty is signified the movement of the alteration, for, since from the ten upwards one advances not except by altering this ten with the other nine and with itself; and the most beautiful alteration which it receives is its own with itself, and the first which it receives is the twenty; reasonably by this number the said movement is signified. And by the thousand is signified the movement of increase, which in name, that is, this thousand, is the greater number, and to increase still more is not possible except by multiplying this. And these three movements alone are observed in Physics, as it is demonstrated in the fifth chapter of his first book.