Another universal theme, sleep (or the lack of it), affects everyone. The poet who cannot get to sleep writes a poem about it. Suffering poets yearn for it, and yet it often eludes those most in need of it: the troubled and careworn. Sleep is usually personified in poetry as the poet addresses it as a god, pleading for it to bring its gifts of revitalizing repose. Sleep is usually seen as the balm that brings about renewal, and the bestknown passage in English describing sleep's restorative powers is Macbeth's tortured speech in Shakespeare's famous play. Having murdered Duncan, Macbeth realizes that his conscience will give him no peace:
Methought I heard a voice cry “Sleep no more!
Macbeth does murder sleep,” the innocent sleep,
Sleep that knits up the raveled sleave of care,
The death of each day's life, sore labor's bath,
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast. (Macbeth, 2.2.39−44, 1606)
Because sleep doesn't come just when we wish it, it is sometimes personified as a fickle lover, and poets often wonder why it visits other people and not them. In its more universal sense (even the worst insomniac sleeps eventually), however, it is associated with death, because the sleeping person most closely resembles the dead. In Greek mythology, the personification of Sleep, Somnus, was Death's brother. He lived in a deep valley, out of the sun and engulfed in shadowy twilight. No sounds disturb his slumber except the flowing of the river Lethe, which brings forgetfulness, another blessing of sleep for a troubled mind. Morpheus, son of Somnus, was the god of dreams, from whose name we derive