Immediately after this, they meet with Sordello, who tells them that it is impossible to climb even one step on the mountain after sunset, and leads them to a flowery valley, in which to rest for the night. The spirits in the valley sing the evening hymn while the sun sets; and it begins to grow dark while Dante is talking with judge Nino, explaining whence he came that morning. As soon as the stars become visible, his eyes seek the southern pole, and fix themselves on three brilliant stars which have taken the place of that constellation of four which he saw some fourteen hours before. The latter have travelled to the south-west, and are hidden behind the mountain, and the new constellation is above the pole towards the east. Night has risen two steps and part of a third in this place when Dante falls asleep, and the most natural meaning of this is that it is somewhat more than two hours after sunset, or after 8 o’clock, in Purgatory. The moon has not yet risen, since she is like a clock which loses on an average 50 minutes every day. Since the first morning in the Forest, when she was exactly 12 hours behind the sun and set at six o’clock, three whole days have elapsed,[465] and if she has lost 3 times 50 minutes, or 2½ hours, she will rise 14½ hours after the sun rises, that is 2½ hours after sunset, or at about 8.30. As the retardation varies much, let us say simply that she rises to-night between eight and nine o’clock. She has also moved among the stars, about 13 degrees each day, and as 3 × 13 = 39, and there are 30° in a zodiacal sign, she has passed out of Libra and is in Scorpio. Libra begins to rise at 6 p.m., and Scorpio at a little before 8, therefore part of Scorpio is now above the horizon.[466] This, then, is the meaning of the first two stanzas of Canto ix.: the mistress of Tithonus is the aurora before moonrise (the solar aurora being his wedded wife, according to classical mythology), and this pale aurora is showing white in her balcony of the eastern sky, while on her forehead shine the stars of Scorpio, the cold creature with the stinging tail. ------------------------------------------------------------------------ [465] See table on p. 361. [466] “We must not assume, as some commentators have done, that the signs rise at equal intervals of two hours, although each circles the star sphere in 24 hours. See fig. 46, where the dotted line shows how _e.g._ Cancer, circling parallel with the celestial equator, will rise at a point considerably north of east, and having had to traverse more than 90 degrees since Aries rose due east, will not rise until about 7 hours later, _i.e._ 1 p.m. Conversely Scorpio, following Libra, will rise south of east, and a little _less_ than 2 hours later. The moon’s retardation, therefore, is less in this part of the zodiac than it would otherwise be, and the hour is probably nearer eight than nine.” ------------------------------------------------------------------------