From Primo Levi’s Survival in Auschwitz:
Sooner of later, everyone discovers that perfect happiness is unrealizable, but there are few who pause to consider the antithesis: that perfect unhappiness is equally unattainable. The obstacles preventing the realization of both these extreme states are of the same nature: they derive from our human condition which is opposed to everything infinite.
Needless to say, this quote is neurochemically accurate. The brain is an equilibrium machine.