"There is something fine in hard physical labor.... One actually stops thinking. I often work long without any thought what ever, so far as I know, save that connected with the monotonous repetition of the labor itself -- down with the spade, out with it, up with it, over with it -- and repeat. 
  And yet sometimes -- mostly in the forenoon when I am not at all tired --- I will suddenly have a sense as of he world opening around me; a sense of happiness, that is near complete content." David Grayson.