The astrological attribution of Key 2 is the Moon. The moon is a reflector of sunlight and thus is a symbol of reflection, duplication, (as in a mirror) and like ideas. The crescent moon is cup shaped, and therefore symbolizes receptivity. These properties are those of the subconscious mind. You will be able to see readily that the factors of reflection and duplication are essential to the faculty of memory, which is symbolized by this Key.
The universal substance has been called by some modern scientists "mind-stuff." Occultists have known for ages that the universe is really made up of mental energy. This primordial substance, known to the Hindus as Prakriti, has always been symbolized by Water and by a Virgin. The High Priestess is a Virgin, and the blue color that predominates in this Key, as well as the flowing robe, represents Water. The curtain behind the High Priestess is a symbol of Virginity. It connects the two pillars of light and darkness, and all other pairs of opposites, thus symbolizing the associative powers of subconsciousness. This symbolism of pairs of opposites is also carried out by the ornaments on the veil, which symbolizes the active and passive modes of the Life-Power's self-expression.
The symbolism of the stone cube is too involved to give here at length, but we may say that STONE is an esoteric word representing Union, Life and Wisdom.
The silver crown represents the waxing and waning of the moon, thus representing periodicity, and rhythm. The scroll represents memory, history, the record of experience. The word TORA signifies Law.