DE MONARCHIA OF DANTE ALIGHIERI
CHAPTER IX: Men, as the sons of Heaven, should follow in the footprints of Heaven.
1. Likewise, every son acts well and for the best when, as far as his individual nature permits, he follows in the footprints of a perfect father.  As "Man and the sun generate man,"  according to the second book of Natural Learning, the human race is the son of heaven, which is absolutely perfect in all its works. Therefore mankind acts for the best when it follows in the footprints of heaven, as far as its distinctive nature permits. Now, human reason apprehends most clearly through philosophy  that the entire heaven in all its parts, its movements, and its motors, is controlled by a single motion, the primum mobile,  and by a single mover, God; then, if our syllogism is correct, the human race is best ordered when in all its movements and motors it is controlled by one Prince as by one mover, by one law as by one motion. On this account it is manifestly essential for the well-being of the world that there should exist a Monarchy or unified Principality, which men call the Empire. This truth Boethius sighed for in the words, "O race of men how blessed, did the love which rules the heavens rule likewise your minds!" 
1. Conv. 4. 24. 8: "All children look more closely to the paternal footprints than any others."
2. Phys. 2. 2: "Homo hominem generat ex materia et sol," Witte quotes from an old Latin version. Dante quotes three times in De Mon. from De Naturali Auditu, as he calls the Physics of Aristotle. Cf: infra, 2. 7. 3; 3. 15. 2.
3. Inf. 11. 97: "Philosophy ... to whoso looks narrowly on her, notes, not in one place only, how nature takes her course from the understanding of God, and from His workmanship; and if thou well observe thy Physics, thou wilt find after not many pages, that your workmanship, as far as it can, follows her as the learner does the master, so that your workmanship is as it were second in descent from God."
4. The "primum mobile" is the ninth heaven, and the source of motion in the other eight movable heavens. The heavens are treated of in Conv. 2. 3-6; the "primum mobile" in 2. 4. 1: "The fervent longing of all its parts to be united to those of this tenth and most divine heaven, makes it revolve with so much desire that its velocity is almost incomprehensible." Dante's theory of motion is to some extent explained in Letter 11. 26: "Everything that moveth hath some defect, and hath not its whole being complete in itself."
Conv. 2. 15. 5: "The said heaven directs by its movements the daily revolution of all the others, by which they all daily receive and transmit here below the virtue of all their parts."
Par. 27. 106: "The nature of the world that holds the centre quiet, and moves all else around, begins hence as from its starting-point. And this heaven has no other Where than in the mind of God, in which is kindled the love that turns it and the virtue that it showers down. Light and love comprehend it with one circle, as it does the rest; and of that girth He only who girt it is the intelligence. Its movement is not marked out by any other, the others are measured by it." Cf. Par. 1. 76, where God is called "Love who orderest the heavens," and De Mon. 2. 2. 3 note.
Par. 28. 70: "The one which sweeps along with it the universe sublime."
5. De Cons. Philos. 2. Metr. 8. 11. 28-30. See pp. 282-288 of Moore's Studies, Vol. 1, for an account of Dante's relation to Boethius, one of his "favorite authors."