One of the main characteristics of the universe is its dualism. Everything appears to come in twos, everything from binary numbers, to the Cartesian mind and body, heaven and hell as well as good and evil of the Christian religion. Even matter has its counterpart in the form of antimatter. It seems that after all, the yin and yang of Taoism applies to all creation in the universe.
We can say that evil is the opposite of good since the one cannot really exist without the other. But what is evil? Evil can be seen as that which creates disruption or disorder. When the universe is in balance and harmony, there is peace and quiet, but the moment something intrudes upon and shakes up the state of equilibrium, there is chaos.