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Then the moon, having finished half its turn, keeps going on,
approaching the sun and with its light diminishing, so that it
appears to us as half, just as at the quarter mark. For when it
has gone three-fourths of its circle it is as close to the sun as
it was in the first quarter. But then it comes closer and
closer to the point that it looks horned,
just as it was before but on the other side. And so it continues
to weaken until it cannot be seen at all since
it is underneath the sun. You can see this well enough
in this figure, so I will not tell you anything more about it.
[rubric:] How the eclipses of the moon come about. [/rubric]

It happens very often
that the moon must
lose its brightness.
And this sometimes (see note) happens
when it is full.
It becomes as though
it were completely spent and