Thomas Traheme (1637?-1674), Hereford born poet, priest and writer, has been variously understood as a nature poet, mystic, or even simply as a facile optimist. Sometimes he has been taken as an honorary Romantic poet, a sort-of Wordsworth before his time. Moreover, it has been common for critics either to divorce his theological beliefs from his literary contribution altogether, or to dismiss his spirituality as undisciplined and immature and his theological views as insubstantial. Based in part on new manuscript evidence, this thesis argues, on the contrary, that Traheme's literary works must be understood in the light of his comprehensive theological vision. Central to this theological vision were the interwoven concepts of felicity, the powers of the human soul, childhood innocence, love and glory, and transfiguration. Transfiguration, for Traheme, was the means by which his goals of felicity, love and glory were attained. For him, the fully human person may by God's grace anticipate even now the experience of final beatitude in which all the powers of the soul are fully employed and enlightened by the Spirit of God. The soul thus transfigured is able in turn 'to transfigure all things, and be delighted' to the glory of God. It is within this sweeping theological vision that Traheme's writings must be understood. It is an articulate vision, rooted in Christian theological tradition and an integrated Renaissance world picture of interdependent spheres, outward and inward, cosmic and anthropological. If we fail properly to appreciate Traheme's theological understanding, then we are in danger of misinterpreting his aesthetic and spiritual contribution. In contrast, when Traheme's devotional prose and poetry are seen in the light of his theological vision, then we are better able to see what Traheme saw - 'a transformed world of glory, inspired with a love as infinite as a creature can hold'. Accordingly, this thesis begins in Chapter 1 with an account of Traheme's biography and his place in the seventeenth century. Chapter 2 reviews the complex story of the Traheme sources, including manuscript discoveries past and present, before turning to a summary of the main lines of interpretation that have emerged in criticism of his writings. Chapter 3 examines the broader context in which Traheme's understanding of transfiguration arises. Chapter 4 traces the ways in which Traheme's anthropology, pneumatology, and eschatology undergird his theological vision of transfiguration. Chapter 5 focuses on a detailed discussion of transfiguration as process and event in Traheme's writings. A final concluding chapter offers a summary account of Traheme's view and demonstrates how this theological vision offers an enriched reading of his devotional prose and poetry while giving particular attention to the concept of transfiguration as action.