Wisdom demands balance. Yet the modern man leads an unbalanced life. He is engaged in ceaseless activity, whether of work or pleasure, without the counterbalance of quiet repose and inner withdrawal. His activity is alright in its place, but it should be kept there, and should not overrun these precious moments when he ought to take counsel of his higher being. Hence the periodic practice of mental quiet is a necessity, not a luxury or hobby. It is called by the Chinese esoteric school "cleansing the mind."
-- Perspectives > Chapter 3: Relax and Retreat > # 7