"To say, 'nothing is true', is to realize that the foundations of society are fragile, and that we must be the shepherds of our own civilization. To say, 'everything is permitted', is to understand that we are the architects of our actions, and that we must live with their consequences, whether glorious 或者 tragic."
Basically its this idea of freedom to think and do how we chose while still holding the responsibility of our actions.
