The Dialogic Imagination, by philosopher and literary theorist Mikhail Bakhtin, is a compilation of four essays that were first published separately and then later put together and published in 1975. The main subject (or theme) discussed by the essays is the novel, from the perspective of literary theory and the philosophy of language. Chiefly, Bakhtin argues that the novel is a fluid, developing artistic genre that can not be easily categorized. In discussing the novel as a literary form, Bakhtin also discusses themes of language, its nature, and its relationship to society.

Each essay focuses on these themes in a slightly different but related way. The first essay is “Epic and the novel." It contrasts the novel as a genre with the epic by comparing the two literary forms. The second essay is "From the Prehistory of Novelistic Discourse." It discusses the history of the modern novel, focusing on how different texts have played a part in its development. The third essay is "Forms of Time and of the Chronotope in the Novel." Here Bakhtin introduces and explores the concept of chronotope, his literary theory about the connections between time and space in literature. The fourth essay is "Discourse in the Novel." It discusses the philosophy of language, with an emphasis on the concept of heteroglossia. This terms refers to the diverse and multiple perspectives and variations within languages and thus discusses how all languages are determined by and connected to context.

Overall, then, the themes can be considered the development of the novel as a genre, its nature and history, its connection to society, and its relationship with language.