Is intelligence a fit topic for intellectual history? The creation and institutionalization of IQ (the initials have become self-sufficient, and no longer stand for “intelligence quotient”) have been a favorite topic in the history of psychology, and have even achieved some standing in social histories of class, race, and mobility, especially in the United States. The campaign to quantify intelligence tended to remove it from the domain of intellectual history, which after all has traditionally emphasized ideas and interpretations. Measurement, and not alone of the mind, was pursued as a way to rein in the intellect by making it more rigorous. What was pushed out the door, however, returned through the window in the form of debates about what intelligence means; in what sense and with what tools it can be measured; and how these measures relate to other ways of comprehending mind, thought, and reason. Quantification, a potent strategy for releasing science from the grip of history, is itself profoundly historical, as a half-century of modern scholarship has demonstrated. This historicizing of the antihistorical embodies what we may call counterreflexivity, and, as such, is partly about puncturing illusions, though it need not take a negative view of the social role of science. The perspective of history is all the more essential because the depoliticization of merit through science entails a consequential moral and political choice. Measurement, by rationalizing and stabilizing the idea of intelligence, enabled it more readily to enter everyday discourse and to be put to work in schools, businesses, and bureaucracies.