There are 3 related Tarot cards, linking darkness with a light.
The first one is the Hermit, the lone wanderer in the darkness, who is guided by his light. He symbolizes the process of learning through own experience, illuminating the irrational darkness around us with the light of his mind.
After the fall brought by the (ivory) Tower of our mind (structure, created by the previous card in the deck) one is left in darkness again. This time it is not the own light that illuminates the path, but a guiding star. A heavenly body, whose existence does not depend on us in the same way it does with light of the Hermit. The Star symbolizes inspiration(breath in), a breath of life from the previous destruction (breath-out). This impersonal guide symbolizes the ray of hope, the eyes that perceive the greater design.
Following the Star, comes the Moon. While the light of the Star is sharp, the one of the Moon is revealing shadows and shapes. The Moon is a universal symbol of irrationality, the emotional nature (in astrology), female fecundity (in numerous mythologies). The Moon has many veils of illusion (linking it to the astrological Neptune), and yet it can also reveal a world of beauty. Now I understand why in the Crowley Deck it has been assigned the sign of Pieces.
These 3 cards offer 3 faces of light in the darkness. Personal, impersonal and irrational. Once your mind illuminates your path, you get a personal sign of destiny, yet part of a something greater, and then you face the irrational aspects of your self.