Is bacon fat meat? Chicken? Cheese? Eggs? All of these have been considered, at different times, meat or meatless foods by the Catholic Church. The eighteenth century historian Le Grand d'Aussy included several long passages on the complex history of Catholic fasting in France in his master work on the history of French food. Taken together, they explore the often surprising twists and turns this practice took from the time of the Franks to his own. Throughout the Old Regime, the distinction between meat and fast-day foods was central to French dining; the exact definitions, however, of what was meat and what was not and what days were to be observed as fast days shifted dramatically over this period. Le Grand, a former Jesuit, was particularly well-qualified to discuss this issue and does so with authority and wit, citing innumerable older sources in a rare, comprehensive study of this practice in France.