About the middle of the twelfth century he gave forth his collection of Sentences, or Statements by the Fathers, and this remained until the end of the Middle Ages the universal manual of theology.

In it was especially developed the theological view of man's relation to the universe.

The author tells the world: "Just as man is made for the sake of God--that is, that he may serve Him,--so the universe is made for the sake of man--that is, that it may serve HIM; therefore is man placed at the middle point of the universe, that he may both serve and be served." The vast significance of this view, and its power in resisting any real astronomical science, we shall see, especially in the time of Galileo.
The great triad of thinkers culminated in St.Thomas Aquinas--the sainted theologian, the glory of the mediaeval Church, the "Angelic Doctor," the most marvellous intellect between Aristotle and Newton; he to whom it was believed that an image of the Crucified had spoken words praising his writings.

Large of mind, strong, acute, yet just--even more than just--to his opponents, he gave forth, in the latter half of the thirteenth century, his Cyclopaedia of Theology, the Summa Theologica.
In this he carried the sacred theory of the universe to its full development.

With great power and clearness he brought the whole vast system, material and spiritual, into its relations to God and man.( 42) (42) For the beliefs of Chaldean astronomers in revolving spheres carrying sun, moon, and planets, in a solid firmament supporting the celestial waters, and in angels as giving motion to the planets, see Lenormant; also Lethaby, 13-21; also Schroeder, Jensen, Lukas, et al.
For the contribution of the pseudo-Dionysius to mediaeval cosmology, see Dion.