The mythical Minotaur—part man, part bull—was Picasso's alter ego in the 1930s and part of a broader exploration of Classicism that persisted in his work for many years. The Minotaur was also emblematic for Surrealists, who saw it as the personification of forbidden desires. For Picasso it expressed complex emotions at a time of personal turmoil. The Minotaur symbolized lasciviousness, violence, guilt, and despair.
The motif of one figure watching another figure sleeping also recurs in Picasso's art throughout his career. Variations include scenes with two women, a man and a woman, and a mythical creature with a woman. The female figures were often inspired by the women in his life at the time. One explanation for the persistence of this theme is the fact that Picasso worked at night and had ample opportunity to observe his lovers sleeping.
Gallery label from Picasso: Variations and Themes, March 28–September 30, 2010.