The author argues that the key distinction in Plato's psychology, as it is elaborated in Phaedo and Republic, is not between soul and body but rather between two aspects of the soul. The main starting point in justifying this argument is an analysis of the theory of recollection that Phaedo presents. This theory, along with the proof for immortality which it proves, requires us to distinguish between two aspects: The soul contains, on the one hand, a perfect and forgotten knowledge – on the other hand, being one phenomenon among many, the soul exists and as part of this existence it recollects some of this perfect and forgotten knowledge. This duality is not one between the rational and non-rational parts of the soul. Recollection involves reason. The duality in recollection is between latent and perfect knowledge, on one hand, and the rational activity by means of which it is revealed, on the other. The opposition that is intrinsic to this duality is hence closely related to Plato's distinction between Ideas and phenomena. It is an opposition between the being and becoming, between the eternal and mortal. In Phaedo, throughout the various arguments and according to the various participants' grasp, this concept is developed and culminates in the last proof: This proof point at the source of life, much like the theory of recollection revealed the source of knowledge. The duality of the soul also elucidates the mythic symbols at the outset of Phaedo. The proofs that this dialogue furnishes for immortality clarify the duality of the soul and in doing so they offer a novel interpretation for the mythical symbols concerning the struggle of the soul which the body imprisons. This external conflict is rendered philosophically meaningful in Phaedo, turning thus into an expression of the basic tension between the two aspects of the soul. The interpretation that this book offers takes issue with more conventional ways of understanding Phaedo's psychology, which usually present it as though it was based on a division between body and soul. By reading this dialogue's arguments with reference to the duality of the soul, the author evokes the coherency of the proofs proposed in Phaedo to the immortality of the soul and clarifies the relationship between Plato's views of the soul as they appear in Phaedo and Republic respectively. Thus he sheds light on the latent dimension of the soul, on the inconceivable depth of the human soul which constitutes the foundation of Plato's philosophy of yearning.