It is a mistake to think of the animal soul as animal-like.
It is an animal in the way that the fox is supposed to be the cleverest of animals.
The former Rabbi Yoseph Yitzchak of Lyobavitch, speaking about his father’s criterion for distinguishing between the good impulse and the evil impulse, said that it was simply a matter of being very precise about what a person desired.
What was its basic quality?
It could even be a matter of a mitzvah or deep concentration in prayer.
What was it if it prevented a person from doing a real good?
Could it not then be considered part of the activities of the animal soul?
The rabbi added: “Till then I knew that the animal soul could be a scholar; now I learned that there could be ‘a Chasid animal soul’ (an animal soul parading as a Chasid).”
From this it may be deduced that the problem of whether a thing is good or evil, the problem of knowing from which soul it comes, may be solved by distinguishing the desire behind it, what the soul wants at that particular moment.
–Rabbi Adin Steinsaltz