Mark S. Massa’s The Structure of Theological Revolutions: How the Fight Over Birth Control Transformed American Catholicism is a study on two levels. On one level, it is a study of the responses of select American moral theologians to Pope Paul VI’s 1968 encyclical on contraception, Humanae vitae (hereafter, HV). On another level, it is a second-order reflection on these theological responses, using them as data, as it were, for a theory about how theology changes or does not change over time. The book certainly succeeds on the first level. I am not sure, however, that that success translates easily to the second level. To the extent that it is possible, I would like to work with these levels successively, even if, for Massa, the two are accomplished simultaneously, since the narration of the “brilliance” (passim) of the individuals treated is tied to the narration of how each of them radically broke with the paradigm of natural law that Massa claims is enshrined in HV.