The shadow side of the human psyche is not to be feared but embraced. What we have rejected, suppressed or ignored in ourselves is exactly what we need to explore and embrace, even if we fear it.
Embracing that part of ourselves which we oftentimes view as the most vile, darkest aspects of our secret (or not so secret) selves is the key to breaking free from the shackles that bind us to the world of suffering.
The last thing our ego wants is for us to admit to and shine a light on those aspects of our psyche that are less than admirable.
We work our entire lives, striving to be right, to look good, to be smart and to earn admiration from others. These are just a few of the illusions we pursue that bring out our shadow side for in striving to be right we make someone else wrong, in striving to look good we admit that others are ugly, in striving to be smart, we place an unnecessary importance on knowledge; and in striving for admiration we fail to see the perfection that lies within each of us.
There are numerous shadow sides and it would be impossible to create such an inexhaustible list. The main point to remember is that when we fail to acknowledge or see the shadow, our soul remains in a constrained, painful state.