This thesis studies the unity of themes in four books of Ovid's 'Metamorphoses'. Its premise is that there are successive bands or clusters (usually book length) of contiguous stories which are closely related by theme, and which explore and vary the ruling cause/theme of metamorphosis within the cluster. The themes this dissertation finds unifying within each book are not the "surface" themes of love, divine anger, and the like, but rather underlying themes related to the tools of poetic creation (such as metaphor, imitation, imago, synecdoche, theater), or to relationships between self and other. In addition, the bands themselves are not static. There is an overall progression through the whole work in the direction of increasing doubt about metamorphosis and increasing abstraction. Chapter One posits a unity for the whole of Book 1, a book most critics find abruptly divided at its center. The analysis builds on well-recognized themes of physical boundary-setting and boundary-crossing in the first half of the book, to embrace more conceptual and literary boundary-crossings involving metaphor and genre occurring in the second half. Chapter Two finds the unity of Book 2 in the themes of imitation, instruction and substitution. Apollo's Palace is analyzed as a temple of imitation, with Phaethon as a figure who both imitates and attempts to substitute for his father. The images on the Palace doors and the advice given Phaethon are analyzed as humorous reversals of Callimachean precepts about originality. Chapter Three finds the central image in Book 8 in the labyrinth, which Ovid associates with ambiguity and repetition. The chapter traces interrelated themes of doubt, labyrinthine reversals and changes of course, repetition, questioning of metamorphosis, and empty exchange. Here, the poem appears to reflect the fact that it has reached its own center, for which these labyrinthine images of confusion, doubt, and repetition serve as a metaphor. Chapter Four analyzes themes of performance, illusion, and the dissolution of theater and metamorphosis in Book 11. The Conclusion traces briefly the progression of themes throughout the whole poem. (Dissertation Abstracts)