Tarot's Major Arcana 15th key, known as The Devil, shows the image of a mythical creature made up of different animals, such as a bat, eagle and goat. The latter's horns also point to this key's association with sign Capricorn. The key represents the illusion of separateness which is presented to our senses by the material world, and which, without inner perception, can be frightening and appear limiting. But this illusion is shattered when we examine how it is caused, and that is through the function of Saturn, Capricorn's ruler. This is simply the contracting, limiting power of the universe, and without it there would be no matter in the universe, nothing solid, no physical reality.
Some versions of this key show the symbol for Mercury at The Devil's navel indicating that he is a product of our own senses, and in qabalistic tarot which shows the Hebrew letters on each key, this one is associated with the letter Ayin, which means "eye as organ of sight". All these clues point to the fact that what exoteric religion calls The Devil is an idea that we ourselves have created by putting too much emphasis on external appearances, without penetrating to how they were caused. The upside-down pentagram on The Devil's head also indicates the wrong assumptions made about the physical level of creation, since the single point of spirit is pointing downwards rather than upwards as in this key's and sign's opposite image, The Chariot, or Cancer. The Devil sits on a half-cube of physical interpretation, rather than the Holistic Cube Of Space sometimes shown in esoteric versions of Key 4, The Emperor, ruled by Mars which is exalted in Capricorn. And the chains around the figures attached to this half-cube are loose and can easily be removed once the illusion of separateness is realized. Positively, this key represents mirth, because this physical world in which we live is not evil, but a source of delight when we realize how it was formed.