This work investigates the historical evolution of the definition of emotion and the methods proposed by ancient thinkers to achieve tranquility. Richard Sorabji, a distinguished scholar of ancient philosophy, utilizes a vast array of primary texts to trace the development of emotional theory from the Stoic school through the transition into Christian thought. He argues that the ancient preoccupation with managing internal agitation provides a foundational framework for understanding contemporary human nature and the pursuit of peace of mind.

Scholars and students of philosophy frequently cite this text as a definitive historical survey of ancient emotional theory. Readers often note the academic density of the prose, which requires a foundational understanding of classical philosophy to fully appreciate the arguments presented.