Introduction to Astronomy

The nobility of the art

...is found to be both more outstanding in its nature and more exalted in its dignity. Since these things are so, why should it terrify a wise man either to track the movements of the stars or to observe the effects of those movements? Especially when, through the frequent experiments of predecessors and the sharp assertions of philosophers, he holds it as a settled fact that the movements of the stars—according to their specific natures—are followed by the happenings of the world. When he sees, from the counsels of the heavens, that the generation or corruption In medieval philosophy, 'generation and corruption' refers to the natural cycle of birth/creation and decay/death. of things is imminent, he should not—as if held back by some misplaced reverence—lack the courage to believe what he knows for certain, or to announce it, or to show it openly. For just as the movements of the elements, the alterations of the seasons, and the general happenings of the world openly follow the heavenly counsel, so too does the principle of the close relationship of the whole to its parts dictate that the movements of every individual thing throughout the world—its birth, decay, growth, decline, and all its alterations—are ordained from that same origin. Diligent investigation, having first laid a foundation of experiments and gathered related data, has finally attained this knowledge: so that if an error should ever intervene, it is not the integrity of the art term: art (Latin: ars); here meaning a systematic body of knowledge or a technical profession, like medicine or astronomy. that is at fault, but rather the ignorance or negligence of the practitioner that is to be blamed.

For it remains the duty of the professor of this art, whenever he undertakes its practice, to approach it fully instructed in the movements and positions of the stars and constellations—down to the degrees and minutes—as well as their natures and influences. He must neglect nothing regarding the natures, qualities, orders, conditions, places, and times of things, ensuring the suitability of the stars is proportioned to the specific situation. If he fails in any of these parts, it is no wonder that he slips into error. Let us, therefore, point out how this error may be avoided. It seems to arise principally from two causes: first, from a small knowledge of the condition of the things which are to be judged (whether a matter should be ascribed to the nature of the thing itself or to the stars); and second, from an unsound conception of the heavenly counsel, from which a mixture and confusion of influences often occurs, making it difficult to choose which one we should follow above the others. Since this is the case, neither in this nor in other arts pertaining to foresight original: providentiam should the portion one has mastered be abandoned simply because one cannot grasp everything. For even a modest amount of knowledge often yields no small fruit, especially in the foreseeing of events. We see that both physicians and others of that kind are sometimes deceived in their own respective arts. Yet, their help is not refused nor is their art disliked on that account. Why then is the error of other craftsmen tolerated, while the astrologer in the court is excluded to his ruin? Indeed, the deception of a physician is often the cause of death, and the error of a sailor The text mentions 'nauta' (sailor) as another profession where error is perilous, contrasting it with the mere verbal criticism an astrologer receives. is grave, yet the astrologer's error often results only in a great verbal reproach regarding his science. Therefore, since greater benefit follows from the truth of this art and less inconvenience from its falsehood, it is not fitting for the art to displease anyone; and its professors must strive with the utmost care so that an innocent art is not rendered hateful due to the fault of an individual.

Chapter 2.

On the effect of the movement of the stars.

A large ornamental woodcut drop cap 'N' at the beginning of the chapter, featuring complex foliate and floral patterns within a square frame.

Now it is fitting to observe the effects of the stars, having first set forth (as ought to be done in every treatise) the subject to be discussed at the beginning. We follow from the start of the treatise the leadership of the stars through the lower world; the observation of the starry nature and every condition and influence follows for every generation and corruption of things. We are, however, constrained by four boundaries...