Catarina Belo explores the question of spirit in the history of philosophy and in various philosophical disciplines, highlighting its meaning and significance for Thomas Aquinas, George Berkeley, and Georg Wilhelm Friedrich Hegel, among other major figures. Belo argues that some of the traditional arguments concerning God, reason, and our knowledge of the world are shared by these philosophers, culminating but not ending in Hegel. In addition, she defends a kind of idealism that is not incompatible with realism.

The book assumes the form a lively dialogue between a student and a teacher-following the literary tradition in philosophy that begins with Plato. The question of the spirit and its varied meanings are examined philosophically from a historical and a conceptual perspective.