The essence of nursing, including its theory, is in the Sorge um the well-being of the sick and the dying. As elucidated by Heidegger in Being and time, the ontological primacy of Sorge, which is primordial to nursing care, is based on the facticity (qua being-in-the-world) that it belongs to the existential structure of Dasein. Only by thinking with Heidegger can nursing theory, as reflective discourse on nurses and nursing, interrogate the fundamental meaning of care and its associated tasks, such as the “lived experience” (Erlebnis) of patients and the education (Bildung) of nurses.