Modern understanding of the Crusades owes its theoretical formulation and its formation as a discipline to the very first international body devoted to the study of the Crusades, the Société de l’Orient Latin, founded in 1875 by the French count Paul Riant (1836-88). From a point of supposed origin—the Jerusalem Crusade summoned in 1095—Riant postulates an originary form valid for all Crusades. An organic model of an individual life from birth to death provides Riant with the guiding metaphor for all Crusades. To this day, the organic model reigns supreme in the academic study of the Crusades, wholeheartedly embraced by the Society for the Study of the Crusades and the Latin East, which, in its publications, adheres to a birth-to-death coverage of the Crusades, “from the First Crusade (1095-1102) to the fall of Malta (1798).” There was never any attempt to determine “what contemporaries understood by crusading.” The goal of Riant, as well as subsequent scholars who theorized about the Crusades, was simply to devise an easy and quick way to identify Crusades. Jonathan Riley-Smith has been more candid that most in what his efforts to give meaning and definitional structure to the Crusades have produced. “They provide,” he says, “a model for identifying [a Crusade],” equivalent to a diagnostic tool by which to recognize a Crusade. No research program was ever engaged in to determine how the earliest conceptual framework for understanding the Crusades was arrived at. This conceptual framework surpassed any theory advanced to explain the Crusades by modern scholars. It was no mere theory, diagnostic, or conjecture. Rather, it was a comprehensive system, predicated on the intelligibility and systematicity of historical data, by which the many and varied actions of Latin expansion in the central, western, and eastern Mediterranean from the middle of the eleventh century to the early twelfth century were woven together into a whole. The master-weavers of this conceptualization of the Crusades were Pope Urban II (r. 1088-99) and ʿAlī ibn Ṭāhir al-Sulamī (d. 500/1106), and this paper bases its arguments upon their contemporary writings. This paper will answer three questions: What commits Urban and al-Sulamī to the supposition of the systematicity of historical data? How do Urban and al-Sulamī resolve the epistemological problem of the one and the many in the Crusades? Why is modern scholarship of the Crusades fixated on origins—a preoccupation of the eighteenth century?