We turn now to the fourth and final of the dialogues devoted to Socrates’s trial and execution, Plato’s Phaedo, which all but ends with the moving description of Socrates’s death. In the great bulk of the Phaedo, prior to this death scene, Socrates attempts to demonstrate that the soul is immortal. Accordingly, we will treat that demonstration and its significance. Yet we recall, from Lecture Two, that the Phaedo also includes Socrates’s very striking confession of his early interest in natural philosophy. Here Socrates not only admits that he was indeed a “pre-Socratic” philosopher, but also tells us why he inaugurated the change in philosophy that has come to be considered Socratic philosophizing. Our study of the Phaedo, then, will have two main purposes: to discuss the arguments for the immortality of soul, and to revisit Socrates’s extremely important autobiographical remarks. Both of these purposes together permit us to grasp somewhat better the nature of the change that Socrates