The belief is that in the world a man's activities are usually, and mostly, devoted to the benefit of himself and the sustenance of his family, whereas in the monastery they are devoted to seeking God. But this is theory. I once heard Ramana Maharshi rebuke those who were sitting in the Ashram Hall. "Some of you are really householders wearing the sadhu's robe, while some of the householders living in the world are really sadhus!" he said.
-- Notebooks Category 1: Overview of the Quest > Chapter 3: Independent Path > # 235