Envy

"All the seven deadly sins are self-destroying, morbid appetites, but in their early stages at least, lust and gluttony, avarice and sloth know some gratification, while anger and pride have power, even though that power eventually destroys itself. Envy is impotent, numbed with fear, never ceasing in its appetite, and it knows no gratification, but endless self-torment. It has the ugliness of a trapped rat, which gnaws its own foot in an effort to escape."

(Angus Wilson)