In 1979 I went to Morelia – viceregal Valladolid – to study the history of the Mexican Church in the eighteenth century. In Miners and Merchants in Bourbon Mexico (1971), I had described the revolution in government projected by Charles III and traced the fortunes of the entrepreneurial elite who promoted the economic expansion of that epoch, concentrating in particular on the great mining city of Guanajuato. Thereafter, in Haciendas and Ranchos in the Mexican Bajío (1978), I analysed the patterns of land tenure and the structure of agricultural production in León. During my research I had already worked briefly in the archive of the episcopal curia of Michoacán, a diocese, which in the colonial period encompassed the territories of the modern states of Guanajuato, Michoacán, San Luis Potosí, parts of Jalisco and Colima. This archive had been confiscated by the state authorities during the Mexican Revolution and at that time was the only collection of diocesan records open for research. My aim was to complete my exploration of Bourbon Mexico by delving into the world of popular religion and conventual piety and thereby approach more closely the thoughts and sentiments of this epoch than had been possible in my previous books.

In the event, the paltry few months of sabbatical leave at my disposal proved far too short a time to master the great mass of uncatalogued documents housed in the Casa Morelos. With over 1,000 legajos for the eighteenth century alone, any attempt even to survey their content was doomed to failure. Moreover, the bias of these records impelled me towards the material and financial side of church life.