 If constant conjunctions were all that is involved, my thoughts about aspirin and headaches would only be hypothetical. For belief, one of the conjoined objects must be present to my senses or memories; I must be taking, or just have taken, an aspirin. In these circumstances, believing that my headache will soon be relieved is as unavoidable as feeling affection for a close friend, or anger when someone harms us. “All these operations are species of natural instincts, which no reasoning … is able either to produce or prevent” (EHU 5.1.8/46–47).