The Purpose of Evil

The seminal book of Chasidic philosophy, the Tanya, teaches that each Jew has two inclinations within themselves. One is good, advising him to follow the Torah and perform Mitzvos, and the other is the opposite.

The first step in this conflict is to ignore the evil inclination, and silence its voice. The next step is “transformation,” where the passion of the Yetzer Hora is turned towards the good, giving greater impetus to the good inclination.

This explains why evil and its desire are necessary: The passion and strength achieved through this conflict cannot be achieved by the good inclination on its own. King David achieved the transformation of enemy soldiers, when they prayed for his victory in battle.