The podcast needed a link to certain discworld quotes, which I couldn't narrow down to one page, sooo, I'm pasting 'em here, and using this as a link for the show notes.  Ignore if you don't like PTerry.

From Witches Abroad:

[...] what was supposed to be so special about a full moon? It was only a big circle of light. And the dark of the moon was only darkness.
But half-way between the two, when the moon was between the worlds of light and dark, when even the moon lived on the edge... maybe then a witch could believe in the moon.
[p. 269]   http://www.extenuation.net/disc/quoteswa.html

From Carpe Jugulum:
 
...a half moon, She distrusted a moon like that. A full moon could only wane, a new moon could only wax, but a half moon, balancing so precariously between light and dark ... well, it could do anything.    http://home.wxs.nl/~jgmetsel/quotes.html#CJ