Classically philosophers have considered envy to be one of the worst of vices, a mortal sin (mistake) because the envious covet or wish to destroy or confiscate the goods held by others, in order to raise themselves up. Envy leads to theft. But these days, whole political philosophies are based on envy, and those who embrace these philosophies consider their wish to take goods or fortune from others just and virtuous.
Psychologically and spiritually, envy arises from judging oneself as lacking or insufficient in comparison to those who possess goods one does not have. In other words, it arises from unfavorable comparison of oneself with others. This is why it is a vice (weakness) rather than virtue (strength). Envy arises from ignorance of one's unique value, which is incomparable to any other. This ignorance enables a feeling of weakness, impotence, and inferiority to someone else.
Virtue arises from self-knowledge, through which one realizes that every One is a unique, one of a kind, manifestation or expression of the Universe (Tao), and thus that one can be neither superior, inferior, or equal to any other being. One's strength (virtue) comes from honestly expressing One Self, which is the same as allowing the One Source (Universe, Tao, Nature) express uniquely through
your unique synthesis of gifts and talents. Bruce Lee had a grasp of the virtue of this type of self-expression.
He who follows the Tao
Is at one with the Tao.
He who is virtuous
He who loses the way
When you are at one with the Tao,
The Tao welcomes you.
When you are at one with Virtue,
The Virtue is always there.
Tao Te Ching Ch 23 (Feng & English translation)