Freud once planned a comprehensive "study of man's love life." Although only fragments of this project ever appeared in print, much of it can be reconstructed from Freud's letters and other sources. After tracing the evolution of Freud's thinking on this topic, the author proposes that there are five functions of the ego which are associated with falling in love. The bliss of falling in love is seen as the result of a revival of feelings that once belonged to the symbiotic phase of infancy. Other findings of Mahler are considered in terms of their significance for the understanding of love.