[639] “The moon’s declination in the zodiac from the equator towards the south pole is as great as towards the north.” _Qu._ xx. 61-63. ------------------------------------------------------------------------ It is only necessary to delete “quod” and “non potuit,” and the whole passage becomes clear and, from the point of view of mediæval astronomy, correct. The author has shown that the moon cannot be supposed to exert any preponderating influence in the northern hemisphere, because her declination south is equal to that in the north. Nor is it of any use, he adds, to say that this declination (south) results from her approaching the earth more nearly on her eccentric orb (see diagram);[640] for (although this does imply an unequal influence) if the elevating influence came from the moon, it would act more powerfully in the south than here in the north, since the nearer an agent is the more powerfully it acts. He goes on to say that the same reasoning rules out the planetary spheres, and here Alfraganus still supports him, for Saturn, Jupiter, and Mars are said to have the perigees of their eccentrics in the south, just like the moon, while those of Venus and Mercury are continually changing.[641] ------------------------------------------------------------------------ [640] The deferent was the equator of her orb or sphere. [641] Ristoro also defines apogee and perigee (“auge” and “opposito d’auge”) as effects of movements on an epicycle, and says that the deferent is “declined” from the ecliptic (“declinato della via del sole,”) part being north and part south, but he does not say whether its perigee is north or south. _Comp. del Mondo._ I. xii. xiv., and III. vii. ------------------------------------------------------------------------