Sri Aurobindo's hopeful view about the establishment of a perfect society on this earth is one which, I must humbly say, does not seem quite in accord with realities. I wish he were right and I were wrong, for it would be delightful to expect such a Utopia to be realized one day. But the raising of human consciousness to the level of superman will not guarantee unity of outlook and attitude. Differences in these respects and, consequently, differences in action will still remain. Take, for example, the difference in attitude towards the world war shown by Sri Aurobindo himself, Sri Ramana Maharshi, and Swami Ramdas. If unity is to be really attained it could only be attained by evolving to a level even higher still than that of superman. And this indeed is the ultimate goal. But there is a further reason for the difficulty of realizing Utopia. When such a goal has been attained there will be no need to reincarnate on this earth, which is, in some ways, a purgatorial planet. That is to say, it is the natural residence for imperfect persons and not for perfect ones.
-- Notebooks Category 13: Human Experience > Chapter 4 : World Crisis > # 243
