The incorporation of subjective elements provided by the patient to medical practice constitutes a new bridge between two historical movements of human culture: naturalism and rationalism. In recent years, medical sciences have identified these movements as patient-centered medicine and evidence-based medicine. By revisiting the paradigms of medicine, theories of causality, doctor-patient relationship models, bioethical principles and examples of clinical studies, their role and meaning has been revised. The applicability for neuroendocrinology has been demonstrated by validating therapeutic results with measurement of health-related quality of life. The need to incorporate the patient's subjective perception poses a challenge that, when accepted, can advance the understanding and care of human beings--ultimately rational, thinking subjects, and therefore subjective--as our species has been defined.