What has traditionally been known as the Moon card refers to a deep state of sensitivity and imaginative impressionability, developed within a womb of deep relaxation. Here we dream and go into trance, have visions and receive insights, wash in and out with the psychic tides, and experience deep mystical and/or terrifying realities beyond our ordinary senses. The full moon and/or eclipse cycle charted by the Magi (as in some of the earliest Moon card images) exemplify this as a mechanism that Nature uses to expand consciousness.
The variants of the courtly lovers (representing skillful use of the sex force) or the man sleeping it off under the tree (use of drugs to alter consciousness) are also traditional avenues for tapping this primal force. Human interest in higher states propels us to the frontiers of consciousness, where we cannot always control what happens. The Moon card represents the ultimate test of a soul's integrity, where the membrane between self and the Unknown is removed, and the drop of individuality reenters the Ocean of Being. What transpires next is between a soul and its Maker.