The vice of envy

All passions devastate the soul, but the most destructive of them is envy. In a sense it is the first passion, because the primary sins such as the fall of Lucifer, the sin of Adam and Eve, and Abel's murder are its offspring. Envy is born in the soul and subsequently devours it. And whereas all the passions produce at any rate some momentary pleasure in the person who experiences them, envy wastes away the soul through continual, sorrow at the happiness of one's fellow-man... This passion is usually well hidden. We must examine our souls closely in order to realize that oftentimes we take no pleasure in another's happiness, and that when things go well for him, or when he receives praise, something inside us becomes irritated.

(From the prologue)