"Whatever the art you may wish to learn -- whether it be acrobatics or violin playing, mental prayer or golf, acting, singing, dancing or what you will -- there is one thing that every good teacher will always say: Learn to combine relaxation with activity; learn to do what you have to do without strain; work hard, but never under tension."
-- Aldous Huxley, The Art of Seeing (New York: Harper & Brothers, 1942), 36-37.
http://www.troubling.info/huxley42.html