The Tanya's eleventh chapter turns the mirror around and examines wickedness with the same precision it applied to righteousness.
The "wicked person who prospers"—the rasha v'tov lo (רשע וטוב לו)—is the exact opposite of the "righteous person who suffers." In this person, the good of the divine soul is subservient to the evil of the animal soul. The kelipah (a shell of impurity) has the upper hand. The divine spark is still there, but it has been pushed down, overpowered, silenced.
Like righteousness, wickedness comes in degrees. Some people sin rarely, in small ways, and only when the evil impulse briefly overpowers them. Others are dominated by desire constantly. Rabbi Schneur Zalman catalogs the gradations with unsettling specificity: there is the person who sins only in action—committing minor transgressions but not major ones. There is the person who sins only in speech—gossip, mockery, slander. And there is the person who sins only in thought—the one who does not act on forbidden desires but cannot stop fantasizing about them.
The Tanya makes a counterintuitive claim here: contemplation of sin is worse than the sin itself. The Talmud in Tractate Yoma says this explicitly. Why? Because of the three garments of the soul—thought, speech, and action—thought is the innermost, the closest to the soul's essence. When a person sins in action, the contamination touches the outer garment. When a person sins in thought, the contamination strikes the core.
But here is the Tanya's revolutionary insight about the wicked person: even at the moment of sin, a person is only called "wicked" temporarily. The divine soul has not been destroyed. It has been overpowered. The moment the person stops sinning, the label lifts. Wickedness, in the Tanya's framework, is not an identity. It is a condition—and conditions can change.