The 18th key of tarot's Major Arcana, The Moon, represents the astrological sign Pisces, ruled by the outer planet Neptune and the imagery suggests the principles of evolution, both physical and spiritual.
The cray fish emerging from the pool in the foreground can be seen as the animal soul evolving as it progresses up the rolling path towards the two towers and beyond, through firstly the mineral level of creation, then the plant level, then the animal and human levels and beyond the two towers to humanity's next stage of evolution. The dog and the wolf on either side of the path represent the process of adaptation which is essential to evolution, as organisms which do not have the genetic mutations which adapt them to their environment do not survive. On a more psychological and spiritual level, this adaptation comes through art and sacrifice.
Scientific research shows that it is our moon which has been paramount on the process of natural evolution from simple life forms in the ocean. It is the constant motion of the tides, produced by the gravitational effects of our moon upon earth's oceans, which has forced organisms to adapt and change.
The Moon also represents the subconscious mind, active in the process sleep of dreaming associated with this key.
Notes and References
- Tarot card "The Moon" from Margarete Petersen's "Tarot"