Abstract Field focuses on the role in political theory of the concept of potentia of the people—power understood as the informal, natural power of the people—as distinct from potestas understood as the formal arrangement of power under the constitution of a given state. In a close analysis of the arguments of Hobbes and Spinoza on popular power and sovereignty, the book critiques democratic interpretations of both theories. While correct about that, the book neglects fundamental dissimilarities in their views of popular power. Of profound importance is the meaning of the concept “multitude”: unlike Hobbes, Spinoza distinguishes between the great mass of individuals and “the wise,” seeing the “multitude” as encompassing most kings. Also, there is a great gulf between their understandings of the “common good.” For Spinoza, obedience to the sovereign, Hobbes’s desideratum, is only compatible with freedom in the context of a state directed to the common good.