Within the depth-psychology corpus, ‘heartbeat’ occupies a remarkably contested terrain, functioning simultaneously as physiological datum, interoceptive signal, cosmological symbol, and psychotherapeutic index. The dominant modern strand, represented by Craig, Porges, and their clinical inheritors, treats heartbeat awareness as the paradigmatic measure of interoceptive capacity: the ability to count one’s own heartbeats without exteroceptive assistance indexes the integrity of the lamina-I–insular pathway and correlates directly with emotional acuity, decision-making competence, and temporal self-perception. From this empirical vantage, the heartbeat is not merely a cardiac event but a recursive signal that anchors felt selfhood in the anterior insular cortex. A second, clinically urgent strand—represented by addiction researchers Sönmez, Şübay, and Verdejo-Garcia—finds that diminished heartbeat perception characterizes substance-use populations, linking blunted interoception to impaired decision-making and relapse risk. A third, cosmological strand—traceable through Campbell and Sardello—treats the heartbeat’s approximately one-beat-per-second rhythm as a microcosmic echo of universal periodicities, encoding in organic time the same ratios found in planetary cycles. Psychotherapeutically, Ogden demonstrates how redirecting a client’s attention away from an anxious, rapid heartbeat can itself regulate autonomic tone. Taken together, these positions reveal the heartbeat as the point where physiology, phenomenology, clinical pathology, and mythopoetic imagination converge most sharply.