> Or is it that the mind, like the moon, is constant though its content continually changes?

I'd go - intuitively - for it. 

And, that the Moon, like mind, doesn't possess its own light. It reflects light, and passes it on. Mind? It reflects ideas (comparable to light, enlightening), and passes them on.

Best, 

Artur Karp (ret.)

Chair of South Asian Studies,

University of Warsaw

Poland