The nine planets seem to depict the complete human journey, a chase after external happiness that at long last eventually returns inward to seek its own intrinsic joy. It all begins with the Sun, the soul itself, the light of consciousness. The soul projects itself into the dark, inert world by reflecting off the mind, the Moon, enabling itself to become conscious of external objects. Some of these objects it wants to embrace, some it wants to avoid. So, it develops intellect (Mercury), enabling it to interact effectively the external world, and a body of senses (Venus), allowing it to tangibly experience and manipulate external sense objects.
The soul is now fully equipped to exert its independent existence (Mars). Cut off from the divine will by operating with complete nonconformity, it must now exert great energy and effort to make its own way in the world. It becomes red with the strain, and often gets into conflicts with other souls similarly exerting their own independent wills.
Becoming frustrated with the results of striking out blindly, the soul eventually seeks wisdom (Jupiter), guidance to help it better achieve its objectives. The side effect of such wisdom is to catalyst an awareness of the limitations inherent in the external world, impelling the soul to lose interest in its quest for external happiness. It then becomes detached, morose and grim (Saturn).
In this depressing situation, the soul seeks radical change (Rahu & Ketu). At first it smashes it’s former goals only to replace them with new external goals (Rahu), but eventually it may begin to smash externality entirely, beginning a radically new quest inwards (Ketu) towards the happiness inherent within its own root, all-illuminating consciousness (returning to the origin, the sun).