Classical Realism represents a science of politics that is distinct from the conventional understanding of science in International Relations. The object of Realist science is the art of politics, which is the development of a sensibility based on practical knowledge to balance values and interests and to make judgments. Realism’s science and its object led to its tagging as “wisdom literature.” This article illustrates that reading Hans Morgenthau’s and Raymond Aron’s work shows how their hermeneutic form of enquiry provides insights into the character of international politics, which conventional understandings do not. Following the example of Morgenthau, the article, first, illustrates how Realism, rather than providing a theory of practice, builds on a science with the purpose to judge knowledge. Realism’s science analyzes the objective conditions of politics, theorizes them, and takes into account the requirements of political practice under contingencies and considerations of morality. The article, second, examines Aron’s take on political practice in the context of the Cold War and politics that built on knowledge without experience to judge knowledge. Morgenthau and Aron’s science helps to capture Realism’s take on politics as an art, how to explicate Realism’s epistemological foundation and value in studying international politics. Doing so, the article, third, contributes to practice theory by clarifying several aspects of Realism’s science. In particular, it shows how Realism captures the art of politics by conceptualizing practice as a form of human conduct thereby offering a more coherent notion of practice than current practice theory.