In a reply to a yechidus query in the winter of 5635 (1874-75), my grandfather said to my father: The yetzer hara, (the evil impulse), is called “animal soul,” not because it is necessarily a brute animal. At times it may be a fox, the most cunning of beasts, and great wisdom is needed to perceive its machinations. At other times it may clothe itself in the garb of an earnest, straightforward, humble tzadik, possessing fine traits of character.
The animal soul manifests itself in each person according to his individual character. One person may suddenly experience a powerful longing to study Chassidus or to meditate deeply on some chassidic concept. The truth is, however, that this is nothing more than the yetzer hara’s counsel and the animal soul’s machinations to prevent him from engaging in the avoda of davening or a similar activity.
Take this as a general principle and remember it always: Any matter that is effective towards or actually leads to active avoda, and is confronted with opposition of any sort, even the most noble, that opposition is the scheming of the animal soul.
My father concluded: Until then I had not known that there can be a “pious” animal soul, let alone a “chassidic” animal soul.