Ten Treatises on Astronomy (Book of Astronomy)

...the shoulder blade original: spatula; this refers to scapulimancy, the ancient practice of divination using the shoulder bone of an animal of some animal. And also many other sciences of augury, such as the voice of some animal, or the song of some bird, or howling, or chirping, or the encountering of some thing, and many others that could be numbered, of which nothing [further] is said at present. ¶ Second, namely: Astronomy, with all its parts, is respected above all others, since it declares—from the disposition of the most noble super-celestial bodies—those things which are in the earth: past, present, and future, as all philosophers agree on this. Hence Al-Farabi Al-Farabi (c. 872–950) was a renowned philosopher and scientist of the Islamic Golden Age whose work "On the Sciences" was a standard textbook in medieval Europe. says in On the Sciences: Astronomy is the science of the significance of the stars—what the stars signify concerning many things: present, past, and future. ¶ Its matter or subject is magnitude itself, as has been said. ¶ Moreover, there are four parts of this division or species. In the first, it treats the site and form of the world and the celestial circles. In the second, it treats the courses or movements of the planets and other stars. In the third, it treats the rising and setting of the [Zodiacal] signs. In the fourth, it treats the eclipses of the sun and moon and other planets. In these parts, almost the whole of astronomy consists.

Universally, there are two species of it: namely, number or computation (as it has a dependency on the first mathematical science, that is, Arithmetic, which is prior to all other doctrinal sciences, for all other mathematical sciences need it, but it needs none of them). The second species of astronomy is Judgment. Computation or numbering is concerned with the definition or knowledge of tables Astronomical tables, such as the Alfonsine Tables, were used to calculate planetary positions.. Judgment is concerned with the knowledge of times, places, and signs; the positions and aspects of the planets; and similar things that harmonize with them.

Its office is to contemplate the courses of the planets and other stars, conjunctions, aspects, angles, successors, and signs falling from the angles (which have already been their angles), and their effects by previous reasoning. Its end or utility is the intention of judging present, past, and future truth through the inspection of the aforementioned things and to be able to know through discussed inquiry. ¶ The instruments of the utility of the science are many: namely, the astrolabe, the quadrant, the hanging armillary sphere and the other armillary sphere, the planisphere, the curved sphere original: curusperium, likely a solid celestial globe, the statua plosica possibly a reference to a specific type of sculptural model or observational statue used for demonstration and similar things. The practitioner of this science is called any astronomer who practices the art of astronomy by name, looking into the law of the stars by previous interpretation. Why astronomy is called by such a name: I tell you that this name is a compound: namely, from astra [stars] and norma which is a "rule"; hence "Astronomy," that is, the rule of the stars, or the practice of the stars, or the operation of the stars. ¶ Moreover, the difference between Astrology and Astronomy is this: astrology holds the truth of the thing as an intellectual or theoretical science. Astronomy, however, is considered by those using it toward its effect, or as an operational science. Regarding the order in which this science should be taught, some have said it ought to be taught before the other mathematical sciences because it is nobler. Some said after Arithmetic, because it needs number. Some said after Arithmetic and Geometry, because it needs number and measurement. To me, however, it seems it should be taught after all the other mathematical sciences: after Music, just as after Arithmetic and Geometry, because it needs harmony just as much as number and measurement.

Chapter Thirteen: That this science should not be condemned, since the Holy Fathers used it.

For it is worthily commended, because the Holy Fathers used it from ancient times; hence those who condemn it do wrong, and especially those who follow or have followed in the footsteps of Abraham. For Abraham instructed the Egyptians and others who, at that time, wished to use astronomy preeminently,

and especially Atlas, who in this science prevailed over all the wise men who then existed, so that he was reputed as if he were a god. And hence it is said that Atlas "supported the heaven" In Greek mythology, Atlas was cursed to hold up the sky; here, the author interprets this as a metaphor for his vast astronomical knowledge. because of this: that he knew more about the super-celestial bodies than anyone who was found in that time. Also even the Lord himself, when he said to the apostles, "Let us go into Judea again," and they said, "The Jews were just now seeking to stone you, and you are going there again?"—responding, he said: "Are there not twelve hours in the day?" John 11:9—as if he were saying: "One hour is good, even if another is bad," because in the "bad hour" they had an evil will against him. For that hour had passed and a "good" one had arrived; hence, knowing this, he knew that the evil will had departed from their hearts. He wished to choose for himself that hour in which they would not harm him. And by this, it is clear that he used "election" original: electione. Elective astrology is the practice of choosing the most auspicious time to begin an undertaking. and did not blaspheme astronomy, as some envious people and detractors do today. Although it was clearly shown above that much utility and much good can follow from the science of the stars and its judgments—both in the foreknowledge of things and in other matters—nevertheless there were some foolish and fatuous men. One of these was that John of Vicenza Giovanni da Vicenza (d. 1265) was a famous Dominican preacher and political figure. The author's use of "hypocrite" suggests a conflict between secular astrologers and the religious orders., a hypocrite of the Order of Preachers [Dominicans], who said that astrology was neither an art nor a science, but was a certain "appurtenance" original: appositiuum invented by some opponents. To them, it seems to me the response should be: they are fools and err, and they shall perish in their own follies and errors. For it is clear to all that astrology is a science and one of the seven liberal arts. And although a brief response was given to them, it does not seem to me that I should omit proving that astrology is an art and a doctrinal science by sufficient and manifest reasons, even though [the order] may seem backwards through them.

Chapter Fourteen: To show that astronomy is an art and one of the four mathematical—that is, doctrinal—sciences.

That astrology is a science is proven by evident reason in this way: Astrology is the science of mobile magnitude which, by inspecting the reason of the celestial bodies, distinguishes the course and motion of the triplicity of time. Or, astrology is the science which investigates the courses of the stars and the habituations and figures of the stars around themselves and around the earth by investigable reason; therefore, by the definition [of the term], astrology is a science. ¶ Likewise, "astrology" is named from astros, which is "star," and logos, which is "discourse" or "science" or "reason" regarding the stars; therefore, through this etymology or interpretation of the name, astrology is a science. ¶ Likewise, it can be proven in another way: everything that is of such a nature that it is from the first true priors, etc., is a science. But astrology has a substantial genus by which it differs from other sciences; [it has its] proper [nature] and accidents; therefore it is a science. ¶ Furthermore, everything that is a collection of precepts tending toward one end is an art or science. Astrology is such; therefore it is an art or science. Augustine St. Augustine (354–430 AD). While Augustine was often critical of fatalistic astrology, medieval authors frequently cited him to support the general study of the heavens. proves this quite clearly, saying: "Art is a precept that gives a certain way and reason for acting or learning." For all the precepts of astronomy then tend toward one end: namely, to knowing or considering things past, present, and future; and in these precepts, the whole intention of astrology consists. Whence Seneca: "To remember the past, to consider the present, to provide for the future"—for those things cannot be rightly looked into except by the astrologer, who has to consider all these things and who alone can know them. ¶ Furthermore, if astrology or astronomy were not an art or science, that famous thing which is universally proclaimed by all would be destroyed: namely, that there are seven liberal arts. There would then be only six, or none at all; for by whatever reason astronomy were not one, by that same reason the [other] six would not be, which would be inconvenient and very dishonorable. ¶ Likewise, since astronomy or...