A patient whose obsessive-compulsive state led to marked inhibition of thought and a total childhood amnesia found himself startled during an analytic hour by an external and unforeseeable outside stimulus—a door rattled. This sound, relevant to the topic being discussed, evoked an affective reaction which had first occurred in childhood and led to the recollection of a childhood event. The affective, motor, and ideational reactions of the patient are compared to the reappearance of a Pavlovian conditioned response by way of an unexpected stimulus.