The totality is the cosmos and, in another sense, the system [composed] out of the cosmos and the void outside [it]. Now the cosmos is limited, but the void unlimited.[1]
The fixed stars are carried along with the heaven;[2] by contrast, the planets are moved in accordance with their own movements. The sun traverses its oblique path through the circle of the zodiac, and similarly the moon [traverses its path] in a spiral [...] Besides, the sun is pure fire [...] is bigger than the earth [...] and it is spherical, analogously to the cosmos. Therefore, [they say that] the [sun is] fire, since it does everything that [is proper] of fire, and it is bigger than the earth because the entire [earth] is illuminated by it, and so is the heaven. And since[3] the earth projects a conical shadow, this indicates that [the sun] is bigger; and on account of its size it is seen from every side [of the earth].
The moon is more like the earth, since it also is closer to the earth. These fiery [bodies] and the other stars are nourished: the sun, insofar as it is an ignited and lazy[4] mass, [is nourished] by the great sea. But the moon, insofar as it is mixed with air and closer to the earth, [is nourished] by [bodies of] potable water [...] The other [stars are nourished] by the earth.[5] They [sc. the Stoics] think that both the stars and the earth are spherical, [the earth] being motionless, and that the moon does not have its own light but receives its light from the sun and is illuminated [by it].
The sun is eclipsed when the moon covers it on the side which is toward us.[6] In fact, at its phases [the moon] is evidently approaching [the sun], and occludes it, and [finally] passes it by. This is verifiable by [the reflection] in a dish containing water. By contrast, the moon [is eclipsed] when it falls into the earth’s shadow;[7] this is the reason why there is an eclipse [only] when the moon is full. Although the moon is in a position diametrically opposite to the sun once a month since it moves obliquely towards the sun’s, it diverges in latitude and comes to be either too far to the north or too far to the south. But when its latitude coincides with that of the sun and the ecliptic, and then is diametrically opposite to the sun, at that moment [the moon] is eclipsed. And its latitude coincides with that of the sun and the ecliptic in Libra[8] and Scorpio and Aries and Taurus [...].