In tarot, The Moon is card XVIII: dogs howling, a crayfish crawling out of a pool, and a path going somewhere you can't see.

It's read as illusion, intuition and the difference between what you know and what you're imagining at 3am. The imagery is eighteenth-century French with older roots. Like most of the deck it doesn't predict; it hands you a very specific mood and lets you argue with it.