centre. For each movable Heaven revolves round its centre, which, on
account of its movement, moves not; and thus each Science moves round
its subject, which itself moves not; for no Science demonstrates its
own foundation, but presupposes that. The second similitude is the
illumination of the one and the other. For each Heaven illuminates
visible things; and thus each Science illuminates the things
intelligible. And the third similitude is the inducing of perfection
in the things so inclined. Of which induction, as to the first
perfection, that is, of the substantial generation, all the
philosophers agree that the Heavens are the cause, although they
attribute this in different ways: some from the Movers, as Plato,
Avicenna, and Algazel; some from the stars themselves, especially the
human souls, as Socrates, and also Plato and Dionysius the
Academician; and some from celestial virtue which is in the natural
heat of the seed, as Aristotle and the other Peripatetics. Thus the
Sciences are the cause in us of the induction of the second
perfection; by the use of which we can speculate concerning the Truth,
which is our ultimate perfection, as the Philosopher says in the sixth
book of the Ethics, when he says that Truth is the good of the
intellect. Because of these and many other resemblances, it is
possible to call Science, Heaven.

Now it remains to see why it is called the third Heaven. Here it is
requisite to reflect somewhat with regard to a comparison which exists
between the order of the Heavens and that of the Sciences Wherefore,
as has been previously described, the Seven Heavens next to us are
those of the Planets; then there are two Heavens above these, the
Mobile, and one above all, Quiet. To the Seven first correspond the
Seven Sciences of the _Trivium_ and of the _Quadrivium_,
namely, Grammar, Logic, Rhetoric, Arithmetic, Music, Geometry, and