Such a scientific astronomy would easily lend itself to the theological conceptions of the time. The realm of perfection above the moon was supposed to be under the direct supervision of God and to be inhabited by spirits. Thus the conjunction and relation of the heavenly bodies were thought to have influence upon human life, and they furnished the basis of the astrology, necromancy, and spiritism so common in the Middle Ages. The ninth heaven embraced all the others. It swept around them all, without interfering with their own special motions, and completed its revolution in twenty-four hours. The ninth heaven was both the source and the limit of all motion and all change. Beyond it lies the eternal peace of God, which the Christian astronomer regarded as “the abode of the blessed.” This was called the tenth heaven or the Empyrean. This, in Dante’s words, is “the heaven that is pure light; light intellectual full of love, love of the good full of joy, joy that transcends all sweetness.” The tenth heaven is Paradise and is within the life of God. It is important to note that the Ptolemaic conception of the universe is the background upon which Dante constructs his _Divine Comedy_ (see diagram, p. 376),[48] and appears in part at least as the cosmological basis of the _Paradise Lost_ of Milton. For thirteen centuries――from 200 to 1500――conviction remained unshaken in the Ptolemaic system of astronomy as an adequate explanation of the universe. Illustration: PTOLEMAIC COSMOGRAPHY (Showing the Epicyclic Movements of Saturn, Jupiter, and Mars in respect to the Earth) =The Mediæval Man at School.= In the eleventh and twelfth centuries there was a revival in intellectual interests that was deep and broad, and the characteristics of this revival will be discussed subsequently (see Transitional Period, p. 329). Our curiosity, however, is aroused upon our entrance into the Middle Ages, as to what the man of the early Middle Ages studied and how much he learned. We must remind ourselves at the outset of the oft-repeated fact that, on the whole, in western Europe, for the first five hundred years of the Middle Ages, the only people who had any book-learning were the churchmen. Furthermore, with them the learning was very meagre. Their purpose in study will show this, for it was to enable them “to understand and expound the Canonical Scriptures, the Fathers, and other ecclesiastical writings.” The training was as follows:―― 1. Theological. Elementary instruction in the Psalms and church music, but no systematic training in theology,――just enough training to enable the priest to understand the Bible and the Church Fathers.