Some scholars who enquire into the doctrine of Plato hold that the main discussion of Plato's Phaidon concerns the immortality of soul. The view of this paper, which argues that Plato's purpose is to investigate the theory of Ideas in the Phaidon, differs from the perspective of other scholars. The immortality of soul is a footstep in Plato's hypothesis, through which Plato shows the world of Ideas. This paper focuses on Plato's Phaidon to explore the relation between the hypothesis and the doctrine of Ideas, and in such foundation to show that the doctrine of Plato's Ideas is the theory of Immanence of Ideas.
