This work investigates the historical transition in eighteenth-century thought from theological conceptions of the soul to naturalistic accounts of personal identity. Authors John Barresi and Raymond Martin, both established scholars in the history of philosophy, utilize a rigorous analytical framework to examine how Enlightenment thinkers moved away from substance-based definitions of the self. By synthesizing primary texts from major philosophers of the period, they argue that this shift laid the groundwork for modern psychological and neuroscientific understandings of human identity.

Scholars and students of philosophy frequently cite this text as a comprehensive resource for understanding the evolution of the concept of the self. Experts highlight the authors' ability to synthesize complex metaphysical arguments into a coherent historical narrative that remains accessible to those with a foundational interest in Enlightenment thought.