To this Key of grotesque and terrible aspect is attributed Mirth. The Devil is that horrible character of exoteric dogmatism which is so ridiculous to an enlightened person. But deeper than this the figure represents the delusion of outward appearance. Key 15 is the opposite of Key 6, hence it shows what happens to us when we fail to use our faculty of discrimination. The ancients declared that the devil is God inverted. This refers to the conception of matter as opposed to Spirit, though the truth is that they are both aspects of ONE THING, as is so graphically symbolized by the interlaced black and white triangles familiar to every student of occultism.
The black background is a symbol of darkness and ignorance. The inverted pentagram on the brow of the devil symbolizes mental inversion, since it is the sign of Man in reverse position. Thus it symbolizes falsehood and delusion. The symbol at the navel of the devil is that of Mercury. The pedestal upon which he sits is a half-cube, symbolizing an imperfect understanding of the physical world, which is represented by a cube. The two figures are personifications of the self-conscious and subconscious minds, and their horns and hoofs indicate that delusion bestializes human consciousness. The chain which holds them to the block of delusion represents Bondage, which is attributed to Key 15.