is practically the only one in which Chaucer gives any hint of the times at which the moon in her various phases may be seen. The phase of the 'new moon,' when the moon is in conjunction with the sun (i. e., between the earth and the sun, so that we cannot see the illuminated hemisphere of the moon) is mentioned in the same poem: "Right sone upon the chaunging of the mone, Whan lightles is the world a night or tweyne."[101] There is a very definite description of three of the moon's phases in the following passage from _Boethius_:[102] "so that the mone som-tyme shyning with hir ful hornes, meting with alle the bemes of the sonne hir brother, hydeth the sterres that ben lesse; and som-tyme, whan the mone, pale with hir derke hornes, approcheth the sonne, leseth hir lightes;" The moon 'shining with her full horns' means with her horns filled up as at full moon when she is in a position opposite both earth and sun so that she reflects upon the earth all the rays of the sun. The moon "with derke hornes" refers of course to the waning moon, a thin crescent near the sun and almost obscured in his light, which approaching nearer the sun is entirely lost to our view in his rays and becomes the new moon. Chaucer's most interesting references to the moon are found in the prayer of Aurelius to the sun in the _Frankeleyns Tale_. Dorigen has jestingly promised to have pity on Aurelius as soon as he shall remove all the rocks from along the coast of Brittany, and Aurelius prays to the sun, or Apollo, to help him by enlisting the aid of the moon, in accomplishing this feat. The sun's sister, Lucina, or the moon, is chief goddess of the sea; just as she desires to follow the sun and be quickened and illuminated by him, so the sea desires to follow her: "'Your blisful suster, Lucina the shene, That of the see is chief goddesse and quene, Though Neptunus have deitee in the see, Yet emperesse aboven him is she: Ye knowen wel, lord, that right as hir desyr Is to be quiked and lightned of your fyr, For which she folweth yow ful bisily, Right so the see desyreth naturelly To folwen hir, as she that is goddesse Bothe in the see and riveres more and lesse.'"[103] In calling Lucina chief goddess of the sea and speaking of the sea's desire to follow her, Chaucer is, of course alluding to the moon's effect upon the tides; and in the line: "'Is to be quiked and lightned of your fyr,'" the reference is to the fact that the moon derives her light from the sun.