Charles Hill, a retired diplomat who taught at Yale University for nearly thirty years, was a visual thinker. In the classroom, he would distill complicated theories of politics and philosophy into simple charts on the blackboard. He taught students to parse the works of Thucydides, Aquinas, and Tocqueville—diagramming concepts of war, glory, law, and religion just as students once learned to diagram sentences. His students would leave these sessions in breathless awe, aware that they had witnessed the remarkable results of a capacious mind engaging with challenging texts.

That visual approach took other forms as well. Professor Hill enjoyed introducing students to Jean-Léon Gérôme’s 1873 painting, L’Eminence Grise, now in the collection of the Museum of Fine Arts, Boston. The painting depicts an imagined scene from the court of Louis XIII. A group of courtiers line a grand staircase and bow to Cardinal Richelieu, who has just moved out of view. Because the viewer is unable to see Richelieu, it appears as though the sycophants are bowing to an ascetically dressed man whose gaze is focused on a book. That man is Richelieu’s advisor: François-Joseph Le Clerc du Tremblay, a Capuchin friar commonly known as his “Gray Eminence” (in contrast to the red robes of the eminent Cardinal). Richelieu, guided from behind the scenes by Père Joseph, transformed European foreign policy in the seventeenth century by centralizing power in France and allying France with Protestant nations in opposition to the Catholic Habsburgs. Gérôme’s painting slyly