The Caduceus Symbol represents the intertwining of positive & negative energies about a central channel

Sushumna - The Central Channel

The 7th Chakra (Crown) is the realm of transcendental Spirit, the location where the universal cosmic consciousness contacts the human individual.  In the Crown, the Divine Love is stepped down to the realm of light.  In the Brow, the drop of divine nectar congeals in accordance with the birth contract initiated by the incarnating Soul.  Then, in the act of creation, the Divine Light is split into the 3 primary rays of light as it penetrates and refracts off the divine drop in the Crown.

In response to the differentiation of light in the Crown, the Sun manifests in the 7th Chakra as the carrier of the life force and signifies the realm of Creator.  In this, Pluto acts as the father, representing the ray of life as it carries within itself the seed of creation from which it manifests.  The seed remains dormant, representing the zero, until the incarnating Soul is granted its birth request and the cosmic dance is initiated.  In response to the manifestation of Creator (1), duality appears as the manifestation of the lower 6 chakras.  In this, the Moon manifests in the 6th chakra and becomes the governor of the material realm.  Here, Neptune acts as the mother, representing the ray of love as it carries within itself the reflection of the opportunity available to the incarnating Soul as it evolves within the material realm.  The union of the Sun and Moon (1 and 2) manifests the created one (3), which is represented by Uranus acting as the ray of wisdom.  Along with the created one comes the realm within which it walks (4) as it moves through time/space.  This ultimately represents the story of the prodigal son.

The manifestation of the Sun in the 7th chakra and The Moon in the 6th chakra represents the division of Heaven/Earth, Spirit/Matter.    In this, the 7th chakra remains transcendental, and the 6th chakra represents the manifestation of that Spirit in its movement through the material realm. Thus, the Sun and Moon signified for 7th chakra are actually representative of the universe Law, not to be confused with the physical Sun and Moon signified for the 6th chakra.  As a reflection of the division of time/space, the universal Moon outpictures in the 6th chakra as the Physical Sun and Moon, representing the duality of female and male, yin and yang, Ida and Pingala.  Then, the created one (Uranus acting as the ray of wisdom), is exposed as the Soul movement through the remaining 5 chakras below the 6th, and therefore exposes the evolution of the Soul as a function of the Ego acting in the moment.

As can be seen from the descriptions above, the lower 5 chakras represent the realm within which the incarnating Soul presents itself, while the 6th chakra represents both the current state of that Soul movement through the physical realm (represented by the Sun) and as a backdrop in the 6th chakra, the dance of shiva manifests as an outpicturing of the original desire to incarnate, represented by the Moon.  Thus, the 6th chakra contains the complete opportunity available to the Soul, and can only be adjusted by the accomplishments actualized by the movement of the Soul through time/space.  At any chakra location of physical form, Ida manifests as the yin (Moon) channel and Pingala manifests as the yang (Sun) polarity for that chakra.  When the forces of Ida and Pingala are balanced and aligned--original desire and created seed are congruent--the Soul receives access to Sushumna where the universal life force there has free movement.  In this, the multitude of minute energy nadis surrounding that location become filled with the Life Force and the division of the male and female polarities at that location begin to merge.  In this, a bridge is created between the two polarities, making the whole range of activity for that chakra available to the incarnating Soul.  The goal of the incarnating Soul is to align the polarities of Ida and Pingala at each chakra location in its movement through time/space. 

In the 6th chakra (Brow), the holographic image of the dance of shiva is overlaid by the dance of life as the incarnating Soul's Ego chooses in the moment.  The Ida force carries with it both the original desire manifested at the birth event and the holographic difference between that perfected state and the current state of the Souls manifestation.  Also, the Pingala force carries with it both the current state of the Souls physical presence, as well as the state of the Souls seed, which contains the culmination of the Souls manifestations throughout life, represented by the dance of life for that Soul.  When the polarities of Ida and Pingala in the 6th chakra are aligned and balanced, the dance of life plays out over the dance of shiva in harmony, and a bridge is created between the Sun and Moon of the physical realm.  As the physical Sun and Moon are carried within the universal Moon reflection, the merging of the polarities in the 6th chakra creates a bridge between the universal Sun and Moon, and the energy in the central channel (Sushumna) ascends to the 7th chakra making activity in that chakra available to the incarnating Soul.  This Merging of the universal Sun and Moon is reflective of the merging of Spirit and Matter, making the divine bliss of the universe available to the Soul through its physical counterpart, the body.