Philosophy
It is much easier to look at someone else and see what is good than it is to look at yourself and see what is good.
It is much easier to look at their situation and possessions and see what is good than it is to look at your own situation and possessions and see what is good.
It is much easier to look at yourself and see what is bad than it is to look at someone else and see what is bad.
It is much easier to look at your situation and possessions and see what is bad than it is to look at their situation and possessions and see what is bad.
And that is the basis of jealousy.
It is much easier to look at their situation and possessions and see what is good than it is to look at your own situation and possessions and see what is good.
It is much easier to look at yourself and see what is bad than it is to look at someone else and see what is bad.
It is much easier to look at your situation and possessions and see what is bad than it is to look at their situation and possessions and see what is bad.
And that is the basis of jealousy.