Krishna - The Moon's Avatar
Vishnu's Avatar for the Moon is Krishna, the advisor the Arjuna.
Krishna is the most famous of Vishnu's incarnations and he is revered the world over for his many profound teachings which can be found in the Bhagavad-gita and Srimad-Bhagavatam.
Krishna taught the importance of bhakti, or loving devotion, as a way to connect one's mind with God in one's heart.
The Moon is the force within us that receive's the good things life has to offer for self-nourishment. Krishna's favorite treat was the butter from the family cow, and the Moon rules both of these nourishing foods.
Krishna also engaged in many questionable activities during his life, such as stealing the butter as a child, and later having many women as sexual partners.
But Krishna eventually devoted himself to Radha, the most beautiful and chaste of all his female followers. Today the two are revered as the divine couple of pure masculinity and femininity.
Sometimes in life people do less than desirable things, but when the Moon is well situated in the chart the person will still feel good about oneself. But if the Moon is negatively affected the person will do good things but still not feel good within oneself.