The Zohar, Chapter “Tazria (When A Woman Delivers),” Item 86: “Who keeps his mouth and his tongue, keeps his soul from troubles.” His soul, which used to speak, is now silent because of the evil words that she spoke. Then comes the serpent, for everything has reverted back to the beginning, as before he was rewarded with a soul. And when the evil speech rises by certain ways to being before the harsh serpent, several spirits awaken in the world, and an impure spirit descends from that side, of the serpent, and finds that the man evoked it with the evil speech. It finds that the holy speaking Ruach is removed from him, at which time the impure Ruach is upon him and defiles him, and then he is a leper.
Where do evil forces come from and what power do they have? They exist only if a person reveals them within himself and decides that they are evil. They are his own uncorrected properties or evil desires. However, if he wants to correct them, they become revealed for the purpose of correction and they aren’t considered transgressions. On the contrary, it is written, “One who comes to be corrected is aided.” That person receives help and doesn’t feel the burden.
However, the evil can also become revealed without a person’s participation, when he is least prepared for it. These are the evil forces he did not correct in the past and is not planning to correct now either. That is when the serpent and other frightening images appear, which are our evil inclination coming to destroy us.
These are all our uncorrected properties which don’t appear according to our desire to reveal and correct them, but in a natural way. They become revealed as evil and harmful forces that act against us.
The Zohar describes it as an outer, alien force which is opposite to holiness. However, it exists within the uncorrected desires of the person himself. Therefore, one shouldn’t think that some unexpected event takes place sent to us by the Creator, but that these events are unfolding only within us. We should always be ready to use any discovery for our correction. Then, it will be for our good.