Methought I heard a voice cry, "Sleep no more!
Macbeth does murder sleep!" the innocent sleep,
Sleep that knits up the ravell'd sleave of care,
The death of each day's life, sore labour's bath,
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast.
-- William Shakespeare (1564-1616), Macbeth
-- Act ii, Sc. 2