Hell is -other people!
Jean-Paul Sartre was a French philosopher and one of the pioneers of existentialism in the 20th Century. The above maxim coming towards the end of "No Exit",a play written by Sartre in the mid '40s, is a play on Sartre's basis on existentialism.
In order to deconstruct this statement and understand it's meaning, I have to put forth and defined some terms.
Noumenon* is a term used to define the cognitive part of the human consciousness. It can also be referred to as the "thing in itself" or the self that is aware.
Noumenon is generally considered to be infinite,having no bounds.However, according to Sartre,any attempt to become self-aware fails as it is an attempt to define the reflective consciousness in an infinite state. The Self (having a conscious boundary) cannot define itself because it is infinite and hence has no bounds .
In order to define self, there needs to be a conscious "Other", which is also infinite in nature. The beauty of the above maxim is in it's interpretation.The protagonist of the play utters the above statement to reject the distorted image of himself that he perceives from the mind of the Others(other characters in the play,audience).This is our Original sin.When we start playing the part in society that is not fundamentally ours we start losing our ties with our Noumenon,our reflective consciousness.When a human being lies,cheats,steals and cons, s/he blames circumstance(noumenon-phenomenon play),society and other forms of conscious "Others". And therein the original personality becomes distorted and fractured.On realising this damned state the conscious mind rejects it as a wrong perception of being when it is seen from the mind of the audience,the people that s/he interact with,friends and family, the others.
The "Hell" that has become the protagonist's consciousness has been transferred to the "Others", a typical human trait!
* not to be confused with a Keralite, ;-)
