Let me begin with an example. My job required me to wake up at 5 in the morning and leave home to be at my stop five minutes early. While waiting for my bus, I would see mendicants sleeping peacefully on the footpath, amidst the chaotic honking of the passing vehicles. It was still a good-night-sleep-tight sleep for those people. The parity between us could be the feeling of joy – doing something we enjoyed : the disparity would be the purpose of life. (I doubt if mendicants have any purpose.)