The Philosophy of Roger Bacon

...round and universal bodies of the world, because there is not one single body for all things, and they possess a single imperfect nature, as was previously stated and cannot be better explained than in the first book of the Physics Aristotle's Physics and elsewhere. Likewise, in the preceding sections, it is by the authority of all, including Ptolemy and Alhazen in the Book of Aspects The Latin title for Alhazen's Optics was 'De Aspectibus', and through astronomy, that vision regarding the stars is understood: when they do not fall at right angles, they are refracted original: "franguntur" before they reach us. If the flow of rays is not in a single medium but divided between an upper part and a nature as has been seen. Through spherical and superior bodies, but the superiors exist by nature in this world. Those lines are to be drawn straight and perpendicularly from the place of the [refraction]. Likewise, it is proved that a body cannot be [diminished?] through itself, just as we see that it is true that what was a rare body and some smaller part—if always by division alone—the dense and the rare are not [made?] as in the case of the upper and lower air. Therefore, just as bodies are divided. Likewise, toward the heavens we see straight motion and circular motion. For we see fire ascend and earth descend by straight motion, and the stars move circularly. But these motions are divided in nature and in time. Likewise, through things movable by straight and circular? motion, there is a division of the world and of time. Likewise, specifically because the world is said to be one in magnitude, in which there is a mode or cause which is the diversity in motions, as the philosophers affirm; they have one axis through the heavens... and essence. This diversity of motions is greater than the diversity of magnitude, because one motion is naturally straight and the division of straight [motion]... as also the rounding, so that it is not easy to see where a straight line ought to rise and what figure it should have. Item, although a straight body can be moved by circular motion, yet it is not its own but accidental, and because of this, no body can have two distinct natural motions at the same time. But [as stated] in the first book of On the Heavens and the World Aristotle's De Caelo, from the divided or compact [parts], motions are divided in time. Wherefore the circular motion of a straight body will be accidental.

original: "Vindica te tibi." This was the personal motto of Sir Kenelm Digby (1603–1665), a later owner of the manuscript and a founding member of the Royal Society.

Round library stamp of the Bodleian Library, Oxford, on the left side of the page.