Something symmetrical might be a butterfly, being looked at from the top. Something that might be asymmetrical might be someones face.
Usually the exposition is where you meet the character and get introduced to the problem.
If Macbeth's conscience had caused him no moral suffering, then he would be an out-and-out villain, somewhat like Shakespeare's Richard III. However, Shakespeare wanted to make Macbeth a somewhat sympathetic figure so that his downfall would seem somewhat tragic
The Title hope that helps :)