Answer: Imagine you were tied to a table covered only with sweets and left this way for the rest of your life. So, what’s next? A person needs a contrast. It is known that people working in the confectionery industry are very fond of herring, and vice versa.
We feel neither sweet, nor bitter, nor salty, nor sour if it has no contrast. Therefore, it is only through good and evil, through the right balance between them, that we begin to develop and attain the Creator.
Good is the absolute property of the Creator, and evil is the complete opposite of Him. We must create their correct combination in ourselves, which will let us feel the Creator.
In principle, good and evil are given to us in order to first attain the outer side of the Creator, and then Him Himself: His intentions regarding us, His original thought, the purpose of creation, and then even deeper—where secrets already begin to be revealed.
From the Kabbalah Lesson in Russian 6/17/18