Taking it in its wider and generic application, I understand faith to be the supplement of sense or, to change the phrase, all knowledge which comes not to us through our senses we gain by faith in others.

Simpson broadens “faith” beyond strictly theological assent to mean a necessary epistemic trust that supplements what the senses can verify. Much of what any person “knows”—history, geography, science beyond one’s own experiments, even everyday reports—arrives mediated through testimony, institutions, and communal authority. By calling faith the “supplement of sense,” he argues that human knowledge is inherently social: we rely on others’ credibility to extend our understanding past immediate experience. In a religious setting, this framing also defends faith as rationally continuous with ordinary life rather than an irrational leap, positioning belief as an extension of the same trust that underwrites learning and civilization.