With key #4 in the Major Arcana tarot series, The Emperor, the first sign of the Zodiac is introduced, Aries. After the "door" of manifestation represented by the previous key, The Empresss, come the spiritual and psychological principles of order, rulership and control to keep this manifestation organized. The ram symbols on the Emperor's throne refer to the idea of God in the Arien Astrological Age or dispensation, in which the deity was seen as a stern ruler demanding sole loyalty and adherence to His laws. The Emperor's steel armor and the red tones of the imagery represent the planet Mars, and its correlations with self defense and initiation of new ideas. Since the sign Aries starts at the Spring Equinox, when nature is renewing itself, this key is secondarily ruled by the planet Pluto, planet of transformation and rebirth, and more commonly known as ruler of Scorpio.
The letter of the Hebrew alphabet associated with this key is Heh, meaning "window", correlating with the Aries rulership of sight, and the eyes, which let light into our consciousness.