The Art of Navigation

Note.

...to include not only the ninth sphere, but also the tenth: for a simple body should only have a single movement, and that one proper and natural: as the Philosopher Aristotle (384–322 BCE), whose theories of physics dominated the Middle Ages and Renaissance. says in the first book of On the Heavens and the Earth: for if it has several movements, these are improper: and since the eighth heaven is a simple body, as the same Philosopher says in the aforementioned place, it is necessary that one of the three movements be proper and natural to it, and the other two irregular. Also, the movement that is proper to it is proper and natural to another: and since it is not from an inferior sphere, one must concede that there are two mobile heavens above the eighth heaven, which cause the two aforementioned movements. And as for what the Philosopher says—that the eighth sphere was the "first mobile"—one must consider that he and the astronomers original: "Astrologues"; in the 16th century, the terms for astronomer and astrologer were often used interchangeably. of his time believed that the eighth heaven had only one diurnal movement, without understanding the two others, because they take place over such a long duration original: "de si longue main"; referring to the extremely slow process of the precession of the equinoxes, which takes thousands of years to complete..

How the Heaven has a round shape, with five reasons why it must be so.

CHAPTER III.

Three reasons why God made the heaven in a round form.

The wisdom of the Eternal Father, by which he created and arranged all things, ordained that the heaven should be round, for the reasons that follow. First, for resemblance. The second, for the reason of profit: and the third by necessity. As for the first, which is for resemblance, because the sensible world The physical world that we can perceive with our senses. is made in comparison to the archetypal world The divine "blueprint" or ideal form of the universe in the mind of God., in which there is neither beginning nor end: thus the sensible world has a spherical form or figure, in which one cannot assign or mark a beginning or end. Secondly, for utility or profit: for among all isoperimetric Bodies that have the same perimeter or surface area. bodies, of which there are four principal ones—oval, pyramidal, columnar, and circular—the sphere is the largest body of all figures, and among all figures the round one is the most capable Meaning it has the greatest volume or capacity to hold things.. And since the round body is the largest, it follows that it is the most capable, and such a form was useful and profitable. The third is by necessity: for if the world had been of another shape than round—namely triangular, quadrangular, or another form—it would follow that there would be some empty space, or some body without a place: although one cannot place any empty space, according to nature: for nature abhors a vacuum original: "la nature en a horreur"; the classical principle that nature will do anything to prevent a void., so much so that she would sooner allow heavy things to rise, or light things to descend, than permit anything to be empty. Aristotle alleges two others...