Note 364 — SECOND PART. The Astronomy of Dante. (continued 2)
Reading edition
See Lubin’s Dante e gli Astronomi Italiani. The period of 225 days may be easily deduced from Ptolemy’s system, for it is the time in which the epicycle of Venus would make an absolute revolution round its centre, the diameter becoming parallel to its former position. But the Greeks invariably reckoned the period as the time in which it revolved relatively to Earth, that is 584 days.