In addition to the sprites and fairies that appear in some of the early comedies (Puck in A Midsummer Night's Dream) and in the later romances (Ariel in The Tempest), Shakespeare includes both ghosts and witches in his tragedies. Although the spirits of Shakespeare's imaginative fairy realms are only real within their domains, and while the ghosts who appear to Richard III and Macbeth are guilty-ridden hallucinations, the ghost of Hamlet and the witches or weird sisters of Macbeth are given substance. Belief in ghosts and in witches remained widespread in Elizabethan England: King James I, Elizabeth's successor and the patron of Shakespeare's dramatic company, wrote a tract on the nature and reality of witches. Shakespeare may not have believed in the supernatural, but he was certainly aware that such beliefs were held by many within English society (including, in the case of King James, those at its top). That being so, he used the supernatural as both a device to advance or embellish his plots and in a metaphorical sense.