"O beware, my lord, of jealousy! It is the green-eyed monster, which doth mock the meat it feeds on."
As Natalie Angier points out in her interesting NYT article on the neurobiology of vice, envy and jealousy are distinct emotions, the latter referring chiefly to possessions potentially lost, the former pertaining to either goods or broader states of being never attained. But we easily recognize them as stemming from the common root of a resentful scarcity of the self. For anyone who has experienced them--and I presume we all have at one time or another--it is hard to say which is more unpleasant, forever gazing up at a desired peak--or falling from it once there. Most of us experience envy or jealousy trivially or transiently; some unfortunate folks make them into a pastime.
Envy apparently has an ancient association with green, perhaps because it was recognized as a kind of moral malady (yellow or greenish skin has long and rightfully been seen as a marker of illness). As Angier notes, envy is a peculiarly ungratifying sort of vice, except when it can be "successfully" discharged as schadenfreude. I think we tend to view the deeply envious as more pathetic than vicious, but all the same it is not a state of mind--advertising as it does the envier's incapacity and ingratitude--that inspires admiration. Envy seems a distinctly spiritual and existential sort of ailment.
The article's least illuminating aspect, actually, is its description of neuroimaging experiments (eventually to be assembled in the Annals of Tautology) designed to show that schadenfreude relates to an area of the brain (the ventral striatum) associated with dopamine and pleasurable experience. We need scanners to tell us this? Do they mean to say that envy, like every other experience, comes from the brain and not from an ethereal soul?
In the psychotherapy literature, envy is advanced as one reason why narcissism is so hard to treat. The narcissist has trouble being healed by a therapist because he envies what the therapist presumably has, i.e. relative well-being and peace of mind. Envy and resentment threaten to undercut the very person trying to help him. This is a distortion of the healthy "idealizing transference" (admiration, basically) that tends to occur in therapy. One admires someone who is seen to occupy a high position that one might conceivably reach as well; one envies the high position that seems unattainable. I suppose the challenge of psychotherapy is to make the unattainable seem attainable, but by constructive self-development rather than by resentful attacks on others. And some find it helpful to regularly practice gratitude as an antidote to envy.
Sociologically we would seem to be the envious species par excellence. The resentment of the technologically and economically backward Muslim world has been blamed, rightly or wrongly, for 9/11 and Al Qaeda. And as capitalism has threaten to careen out of control in recent decades, our keeping-up-with-the-Joneses status anxiety, i.e. envy, has been widely cited. Buying the McMansion, the late model car, the newest Ipod: all are preventive measures for envy, but like a colonoscopy (how's that for a metaphor?) these acts buy tranquillity only for a while. Envy is an evolutionary treadmill of the mind; at some point one just has to jump off.