Gratitude occupies a structurally significant position across depth psychology, classical philosophy, spirituality, and neuroscience — a convergence that reveals its status as far more than a social pleasantry. In the Kleinian framework, gratitude is the developmental counterpart to envy: where envy spoils the good object, gratitude receives and internalizes it, becoming the foundation for character, generosity, and the capacity for love. Melanie Klein locates gratitude’s roots in the earliest feeding experience, making it an index of psychic health at the deepest ontogenetic level. From the phenomenological-spiritual tradition, Kurtz and Ketcham argue that gratitude has been evacuated by a culture that has lost the concept of genuine gift — a loss with profound spiritual consequence. For the Alcoholics Anonymous tradition they analyze, gratitude is inseparable from surrender: sobriety experienced as gift, not achievement, generates a gratitude that transforms the self. Classical scholarship, particularly Konstan’s reading of Aristotle, situates gratitude within the Greek ethics of reciprocity, charting its ambiguous status as both emotion and moral obligation. Contemporary neuroscience, represented by Damasio, grounds gratitude in measurable neural correlates linking it to stress regulation and moral cognition. The polyvagal tradition, via Dana, frames everyday micro-moments of gratitude as ventral vagal resources that strengthen autonomic regulation. The cross-disciplinary picture is one of gratitude as simultaneously intrapsychic capacity, relational virtue, neurobiological state, and spiritual orientation.