Chapter 28: On the subject-matter of astronomy

1. The subject-matter of astronomy is made up of many kinds. For it defines what the universe is, what the heavens, what the position and movement of the sphere, what the axis of the heavens and the poles, what are the climates of the heavens, what the courses of the sun and moon and stars, and so forth.

Chapter 29. On the universe and its name.

1. _Mundus_ (the universe) is that which is made up of the heavens and earth and the sea and all the heavenly bodies. And it is called _mundus_ for the reason that it is always in _motion_. For no repose is granted to its elements.

Chapter 30. On the form of the universe.

1. The form of the universe is described as follows: as the universe rises toward the region of the north, so it slopes away toward the south; its head and face, as it were, is the east, and its back part the north.

Chapter 31. On the heavens and their name.

1. The philosophers have asserted that the heavens are round, in rapid motion, and made of fire, and that they are called by this name (_coelum_) because they have the forms of the stars fixed on them, like a dish with figures in relief (_coelatum_).

2. For God decked them with bright lights, and filled them with the glowing circles of the sun and moon, and adorned them with the glittering images of flashing stars.