It is in fact God (and the side of holiness) that gives power to the Sitra Achra (the Other Side / the forces of evil) to be able to rise itself over the side of kedushah (holiness). This is in order to give us the opportunity to overcome it and ultimately cast it to the ground and humble it. This is the goal.
When one begins the process of seeing the grossness of the physical world, one begins to realise what the nature of the Sitra Achara (the Other Side) really is. One must then cast the Sitra Achra down to do away with it (as its mission is to conceal Godliness from us.)
When a person finds himself with Timtum HaLeiv (a dullness in his heart) and he finds it hard to involve himself in the service of the heart (i.e. prayer), the Alter Rebbe tells us that he needs to break his animal soul. He uses the example of the Zohar that with a beam that does not catch alight, we must break the beam up into smaller pieces so that the fire will begin to catch on it. So too we do the same to our souls. We must break the part of ourselves that prevents the light (of Hashem – our Godly souls) from penetrating through.
The essential soul of the Beinoni — his very essence is really his animal soul. It is that that he associates with. On the other hand, each morning, when we awaken, we thank God for bestowing within us a Godly soul.
We conclude chapter 27 – the middle chapter of a series of three chapters dealing with concepts of overcoming depression and dealing with unwanted sinful thoughts. These thoughts can come to one when involved in mundane work affairs, and they can also come to one when one is involved in one’s service to God (praying for example.)
When the Beinoni is faced with thoughts that come from the Sitra Achra (negative thoughts, thoughts of sin etc.) he should push these thoughts aside. This is known as Itkafiya (Aramaic – meaning subjugation). He should not allow the thought to dwell inside himself.
When one is distressed and one even feels depressed over matters relating to the spirit and certainly at times when we are serving God then we all should know that these are just the ploys of the evil inclination.