When jarred, unavoidably, by circumstances, revert at once to yourself, and don't lose the rhythm more than you can help. You'll have a better grasp of the harmony if you keep on going back to it. -Marcus Aurelius (Meditations Bk. VI, XI.)
Envy is a widespread human emotion, and has quite a broad range; it arises from small, petty observations (jealousy of another person's luck with green lights on a busy street) or from more outstanding realizations (envy for another's financial success).
Recently, we watched the film 13 Conversations About One Thing in my philosophy of happiness class. It was a very interesting movie, and artfully filmed. The film focused on a group of people who had varying definitions about happiness and how it is achieved.
One character stood out. Gene English is portrayed as an insurance company manager, who is constantly under the extreme stress involving his drug-addict son. He has an unhappy demeanor, and this is displayed in many dialogues with different characters. Perhaps the most interesting observation is his seemingly envious attitude toward one of his co-workers, Wade Bowman. Wade's character is exactly the opposite of Gene; he has a generally happy attitude and laughs and smiles often - some of the typical signs of contentment. But Gene is so encumbered with chaotic life circumstances and unhappiness that he is openly jealous of Wade's happiness. In one point in the film, Gene, seemingly purposely following his agenda to avoid happy people, lays off Wade.
This brings up an interesting difficulty in attempting to define the nature of happiness. Of course, many philosophical schools (including the Stoicism of Marcus Aurelius or the zen practices of D.T. Suzuki) attempt to distance the self (ego) from the lived circumstance. But, technically, the lived experience is not the same thing as another human being. Such philosophies realize the need to distance the self from the environment, but largely seem to ignore the jealousy that is bound to arise from one who experiences a less fortunate life excerpt than another who experiences advantageous standings.
The conflict is apparently epistemological in nature, for it deals with the realization of the more prosperous circumstance of the other person. Interestingly, envy seems to have nothing to do with actually perceiving the advantages of another (as in Gene's case with Wade). Let's take the thought experiment of the two prisoners. Two prisoners are serving seperate life-sentences for some extreme crime. Both prisoners are in solitary confinement and cannot, in any way, perceive one another; both have been in confinement for a considerable amount of time. Tiresome and isolated from human contact, the inmates sit alone. One of the prison guards give one of the prisoners a battery-powered radio so he can listen to the radio while serving his time. When the guard reveals to the second prisoner that he had given the other inmate a radio, he will surely become infuriated with intense envy for the other prisoner. No perceptions were made for this result. All that was needed to create envy in the second prisoner was the fact that some sort of existential injustice has occurred. This does not sit well with him.
In the thought experiment, no perceptions were made by the envious prisoner. It is also interesting to note that he would not feel envious if the other prisoner did not exist. If the guard laid the radio in an empty solitary cell and then told the prisoner of his actions, the prisoner would not feel envious. So, it is reasonable to conclude that certain feelings of happiness could become affected by the observable advantages of others.