c. 16. LUCIUS is now ready to speak, but ARISTOTLE intervenes with a reference to the view, held by his namesake, that the stars are composed of something essentially different from the four elements, and that their motion is naturally circular, not up or down. LUCIUS points out that it is degrading to the moon to call her a star, being inferior to the stars in lustre and speed, and deriving her light from the sun. For this, the view of Anaxagoras and of Empedocles, is the only one consistent with her phases as we see them (not that quoted from Posidonius the Stoic). cc. 17, 18. To an inquiry from SYLLA whether the difficulty of the half-moon (i. e. how does reflexion, being at equal angles, then carry sunlight to the earth, and not off into space beyond us?) had been met, Lucius answers that it had. The answer given was: (i) Reflexion at equal angles is not a law universally admitted or true; (ii) there may be cross lights and a complex illumination; (iii) it may be shown by a diagram, though this could not be done at the time (such a diagram is supplied by Kepler), that some rays would reach the earth; (iv) the difficulty arises at other phases also. He repeats the argument drawn from the phases as we see them; and ends with an analogy: Sunlight acts on the moon as it does on the earth, not as on the air; therefore the moon resembles earth rather than air. c. 19. This is well received, and LUCIUS refers (a second analogy) to solar eclipses, and in particular to a recent one, to show that the moon, like the earth, can intercept the sun’s light, and is therefore, like it, a solid body. The fact that the track of the shadow is narrow in a solar eclipse is explained. c. 20. LUCIUS continues his report, and describes in detail what happens in a lunar eclipse. If the moon, he concludes, were fiery and luminous, we should only see her at eclipse times, i. e. at intervals, normally of six months, occasionally of five. c. 21. PHARNACES and APOLLONIDES both rise to speak. APOLLONIDES raises a verbal point about the word ‘shadow’; PHARNACES observes that the moon does show a blurred and fiery appearance during an eclipse, to which LAMPRIAS replies by enumerating the successive colours of the moon’s face during eclipse, that proper to herself being dark and earth-like, not fiery. He concludes that the moon is like our earth, with a surface broken into heights and gullies, which are the cause of the markings. c. 22. APOLLONIDES objects that there can be no clefts on the moon with sides high enough to cast such shadows. LAMPRIAS replies that it is the distance and position of the light which matter, not the size of objects which break it;