It is difficult to think of any Shakespearean play which does not reflect one way or another popular beliefs and superstitions of his day regarding such supernatural elements as ghosts (spirits), fairies, and witches. But R3, MND, JC, Hamlet, Macbeth and Tempest are, among others, the plays whose supernatural elements play a very prominent part with their participation in and influence upon their plot and action. The present article aims at introducing spiritualism or popular superstitions, supernatural and astrological, that were current in the 16th and 17th centuries in general and in Elizabethan and Jacobean England in particular by way of providing a background knowledge of Shakespeare. For this purpose have been discussed somewhat in detail four representative source-books which include Lavater`s De Spectris (1572; R. H.`s English translation, Of Ghostes and Spirites Walking by Nyght, 1572), Scot`s Discouerie of Witchcraft (1584), Le Loyer`s IIII Livres de Spectres ou Apparitions et Visions d`Esprits (1586; Z. Jones`s English translation, A Treatise of Specters or straunge lights, Visions, and Apparitions appearing sensibly vnto men, 1605, includes BK I only), King James`s Daemonologie (1597) and ``Discourse vpon Diuels and Spirits`` added to Scot`s 1665 edition of The Discouerie of Witchcraft. Both books by Lavater and Le Loyer which represent respectively the then Protestant and Catholic views of ghosts together with the ``Discourse vpon Diuels and Spirits`` have much bearing on Shakespeare`s ghosts in general and King Hamlet`s ghost in particular, and both books by Scot and King James on Shakespeare`s witches and witchcraft in general and Macbeth`s witches in particular. In a nutshell, Catholic Church embraced the then ghost-belief that the ghost of the departed could return to earth from the Purgatory to visit his family and friends with various intents, whereas the Protestants who rejected the existence of the purgatory did not believe in such a ghost unless it was a devil which could assume whatever shape it pleased to do harm. Scot was sceptical about the existence of witches and witchcraft and therefore did not approve of the indiscriminate witch-hunting and severe punishment of witches, but King James was a firm believer not only in their existence but also their harmful ways and evil practices, and as a result he did what he could to arrest alleged witches and to punish them. Shakespeare was not the only playwright who utilized the supernatural elements and superstitious traditional beliefs for his plays, but the only one who made use of them in such a way that the supernatural elements like fairies, ghosts and witches played a very vital role and influenced the plot and action of the play. Hamlet without King Hamlet`s ghost, Macbeth without the Weird Sisters, and MND and Tempest without their fairies would simply be inconceivable. It is no wonder that his plays are often called rich source-books for folk-lore. In conclusion, Shakespeare`s creative use of the supernatural elements and traditional popular beliefs achieved the maximum dramatic effect, thus demonstrating Shakespeare`s excellence as a playwright.