Envy

envy - [a] painful or resentful awareness of an advantage enjoyed by another joined with a desire to possess the same advantage. - Merriam Webster

envy - "a reluctance to see our own well-being overshadowed by another's because the standard we use to see how well off we are is not the intrinsic worth of our own well-being but how it compares with that of others" - Immanuel Kant, The Metaphysics of Morals,  1797

I had some difficulty visualizing this word as a young person, partly because of the feelings associated with it and the fact that I never bothered to look it up. Plus, my mind was focused on a singular view point; from the perspective of  the envious person and therefore I could not see the concept clearly.

To visualize envy I had to see two objects; the one who envies and the one being envied. Imagine two equally sized stars, one bright and one not so bright. It is the brightness of the one which illuminates the darkness of the other. This causes the darkened object to see himself more correctly (relatively speaking). If the person has a misdirected view of himself the light would hurt. The motivation then would be to eliminate or reduce the severity of that discomfort...