This thesis aims to demonstrate that Shakespeare encoded his comedies with spiritual arcana including: theurgy; Celtic mysticism; alchemy; Renaissance Platonism; and the Bible. An analysis of The Comedy of Errors and A Midsummer Night's Dream shows that the plays are polysemous, providing simultaneous readings of a number of spiritual allegories. The arcana are examined in the light of material to which Shakespeare could have had access. They are separately documented in chapters designed to provide a resource of information on their contemporary nature mediated for modern understanding. The research is based on an exploration of plays in production, represented in programme notes in the appendices. The work was undertaken to clarify the director's notes to cast and audiences of the international professional Theatre Set-Up company and the results of this study informed their productions from 1983 to 1996. It was found that explanations of the scripts' iconography which the research revealed, clarified and lightened their performance. Early chapters review a range of opinions from literary criticism on the issues discussed in the thesis, revealing considerable sympathy with its tenets.