Black magic is a kind of occult knowledge which misuses the dark forces of the lower vital and subconscient domains. It is mostly used to harm or hurt people out of enmity or some such dark motive. It moves the mind to dark depressing thoughts and suggestions, or fills it with unknown fears. Its spell can create confusion and disturbances in the heart, restlessness, disorder and disintegration. Its most dangerous effect is loss of faith and hope as well as paralysis or perversion of will. By these means it creates a ground for the invasion of adverse forces that bring about various physical and mental illnesses including possession, seizures and madness or insanity. The doors are often opened through vanity and insincerities in nature, as well as through fear and weakness of will.
It does not mean that all can be attacked or affected by black magic even if it is consciously directed by someone to harm. In those endowed with faith, trust and dependence upon God, in those with a clear discerning intelligence, in those who have humility and a fundamental sincerity the effect of black magic is minimal or none. Those who remain sheltered and surrendered to the Divine and are in the habit of calling God’s Name are unaffected by it especially if they have a strong basis of equanimity and peace. In such persons the black magic does not work and often falls back upon the person who was trying to harm.
About Savitri | B1C3-11 Towards Unity with God (pp.31-33)