The blessed AUGUSTINE asks, in chapter 9 of book 2 On Genesis according to the Letter, why the authors of the sacred writings did not openly and explicitly teach what was the nature of the heaven, of what figure, how great its magnitude, and the number of the celestial orbs, what their motion, what the efficient cause of celestial motion, how vast and various the power and efficacy of the heavenly bodies, and many other things of this kind, by which both Philosophers and Mathematicians, in cleverly investigating and subtly treating them, have merited undying praise for their genius and lasting remembrance of their name. To this question Augustine answers very briefly: that the Holy Spirit, by whose inspiration and impulse they were stirred to write, and by whom they were ruled and guided in writing, did not wish things of this kind to be inserted and mingled with the Sacred writings, because they would furnish a knowledge more curious than useful, and it would come to pass that men (such is the human mind's bent toward worse things), in the treatment of such matters, with more useful things set aside, would be wholly engaged and occupied. For had not Moses followed this course, how many things in this place about the celestial bodies and about universal nature he could have marvelously disputed and philosophized! since from that speech of the blessed Stephen which Luke reports in chapter 7 of the Apostolic History, it is sufficiently evident that he was learned and excellently versed in all the wisdom of the Egyptians. Did not Solomon—as it is written in the third book of Kings, chapter 4, and in the book of Wisdom, chapter 7—have a knowledge of all natural things, both celestial and those that are beneath heaven, both ampler and far surer than any of the wise men of this age? Yet God did not wish this so great learning and wisdom of his to be committed to writing and to come to our knowledge, lest, namely, men—whose disposition is of itself prone enough to vain and futile things—should superfluously, and to no profit for the right ordering of the present life and the...²

...attainment of the eternal life, pursue beyond measure things that contribute nothing to it; while the more useful things, and those most profitable for the correction of vices, the establishment of good morals, and the attainment of immortal glory, they would embrace with less zeal and care. Yet many things, and those excellent, are found scattered here and there in the Sacred books from the knowledge of celestial things, cast forth, as it were, as certain seeds many ages before the Philosophers and Mathematicians. Nor indeed is there anything in the science of the stars, either concluded by necessary reasonings or explored and ascertained by manifest experiments, that is contrary or discordant to the divine Scripture; rather, very many of the decrees of astrological doctrine agree and accord with it wonderfully. Wherefore I have resolved to write this book On the Heavens and the heavenly bodies, and in it to explain, not negligently, the harder and nobler questions concerning heaven and the heavenly bodies, according to sacred Scripture and the doctrine and judgment of the Fathers, with theological and philosophical reasonings adjoined besides.³

These, then, are the questions which we have undertaken to treat in this volume. First, whether the heavens and the stars are of an incorruptible nature. Second, what shall be, after the day of judgment, the change and renovation of the heavens. Third, on the figure of heaven. Fourth, on the number of the celestial orbs. Fifth, whether the heavens move themselves by their own natural force, or are moved by Angels. Sixth, whether after the day of judgment the motion of heaven shall wholly cease. Seventh, whether the heavens and the stars are truly animate. Eighth, whether the heavenly bodies are actually hot. Ninth, whether the stars are fixed in their orbs and revolved only by the motion of these, or whether—the heaven being unmoved—they are driven by their own proper motions, just as fish in the water and birds through the air accomplish their motions. Tenth, whether the multitude of the fixed stars which are in the eighth orb is innumerable to mortals. And these will be treated in the first part of this book. But the latter part will contain a good long disputation, against the Astrologers, on the Divination which is drawn from the stars.⁴