Assume a virtue, if you have it not.
That monster, custom, who all sense doth eat
Of habits devil, is angel yet in this,
That to use of actions fair and good
He likewise gives a frock or livery,
That aptly is put on…
-Hamlet (act III, sc. 4, line 160) by William Shakespeare
Duality is a conflict for the unenlightened. Those initiated into the deeper realities of meaning know that there is no duality, for ultimately duality is an illusion. Dualities are not in opposition but are complementary aspects of reality.
Since the Body tends to deal with things that are of the outer world, meaning things that aren't "Me", there has been a tendency to call it "Evil". The Mind/Spirit tends to deal with the inner world, our "personal selves"; it gets labeled "Good". Thusly we get the classic "the spirit is willing but the flesh is weak" interpretation.
For some the Mind/Body conflict is a battleground, but there is no real conflict. You are neither your Body, nor your Spirit, but both in a complementary relationship. The Body provides a medium for interacting with the outer world that the Mind, the inner world, cannot otherwise experience. In return the Body gains thinking which provides better ways to fulfill its needs (Food, shelter, sex, etc…). The Body will not last very long without a mind in charge to say "Hey, don't walk off that cliff", and the Mind has no other tool to Knowledge without the Body.
Among the Egyptians there was an early representation of the gods Horus and Set that shows them as one individual with two-heads. The Set head faces backwards, and the Horus faces forward. This is quite telling when you consider what they are gods of. Set is a god of storms, violence, terror, and generally the more chaotic aspects of reality. Horus is a god of noble virtue, loyalty, love and generally the more ordered aspects of reality.
What we are being shown here is the nature of duality. Order and chaos are both different aspects of the same cosmic body, and not only that, but we see their ideal relationship. Set is a representation of the desires of the lower self connected to the physical side of nature, while Horus becomes the higher self connected to the spiritual side of nature. However note that Set looks backward, and Horus sees forward. The lower self can only see the past, and present. It lacks foresight, and indeed most problems arise when it's in the driver's seat. The higher self needs not to look back, its been there learning those lessons, and now devotes its energies to progress.
Consider the association I have set-up, Horus as forethought, and Set as afterthought. Now compare this to Prometheus ("Forethought") and Epimetheus ("Afterthought"). Prometheus rebelled against Zeus to benefit mankind. In revenge, Zeus gave his brother Epimetheus the first woman, Pandora as his wife. Epimetheus (lower self) ignored Prometheus's warnings (higher self's reasoning), and took her as his wife because Prometheus ignored Epimetheus's needs. This command reminds the magician that one must balance the needs of both the flesh and the spirit to maintain proper health, and spiritual harmony.
