The definition of love given by Descartes in the Passions of the Soul (art. 79-84) has never stopped puzzling commentators. If the first Cartesians textbooks discreetly evoke or even fail to discuss Descartes' account of love, Spinoza harshly criticizes it, pointing out that it is "on all hands admitted to be very obscure." More recently several scholars have noticed the puzzling (or even paradoxical) character of the articles of the Passions of the Soul on love and hate. In this paper we would like to propose a reassessment of the definition and the phenomenology of love provided by the Passions of the Soul and the Letters to Elizabeth and Chanut. By tracing back Descartes' scholastic sources (namely Aquinas' treatises on passions and charity in the Summa theologiae), we will demonstrate how Descartes builds up his definition of love by displacing or subverting the meaning of several major elements of the thomistic vulgata. Hence a significant part of the obscurity of the definition given by the Passions of the soul possibly finds its ultimate rationale in this attempt to recover some traditional questions of the scholastic debate on love, while advancing new answers to them.