The work analyzes how minds apprehend and accept propositions by distinguishing three mental modes—doubt, inference, and assent—and three grammatical forms—interrogative, conditional, and categorical. It differentiates notional (intellectual) from real (affective or religious) assent, examines certitude and varieties of inference (formal, informal, natural), and develops the notion of an illative sense, an habitual practical reasoning faculty that converts probability into conviction. Throughout, it applies these distinctions to questions of natural and revealed religion, showing how theological propositions are grasped, appropriated, and affirmed by different faculties of intellect and imagination.