 But at a certain point—so says this hypothesis about the chronology of the dialogues—Plato began to use his works to advance ideas that were his own creations rather than those of Socrates, although he continued to use the name “Socrates” for the interlocutor who presented and argued for these new ideas. The speaker called “Socrates” now begins to move beyond and depart from the historical Socrates: he has views about the methodology that should be used by philosophers (a methodology borrowed from mathematics), and he argues for the immortality of the soul and the existence and importance of the forms of beauty, justice, goodness, and the like. (By contrast, in Apology Socrates says that no one knows what becomes of us after we die.) Phaedo is often said to be the dialogue in which Plato first comes into his own as a philosopher who is moving far beyond the ideas of his teacher (though it is also commonly said that we see a new methodological sophistication and a greater interest in mathematical knowledge in Meno). Having completed all of the dialogues that, according to this hypothesis, we characterize as early, Plato widened the range of topics to be explored in his writings (no longer confining himself to ethics), and placed the theory of forms (and related ideas about language, knowledge, and love) at the center of his thinking. In these works of his “middle” period—for example, in Phaedo, Cratylus, Symposium, Republic, and Phaedrus—there is both a change of emphasis and of doctrine. The focus is no longer on ridding ourselves of false ideas and self-deceit; rather, we are asked to accept (however tentatively) a radical new conception of ourselves (now divided into three parts), our world—or rather, our two worlds—and our need to negotiate between them. Definitions of the most important virtue terms are finally proposed in Republic (the search for them in some of the early dialogues having been unsuccessful): Book I of this dialogue is a portrait of how the historical Socrates might have handled the search for a definition of justice, and the rest of the dialogue shows how the new ideas and tools discovered by Plato can complete the project that his teacher was unable to finish. Plato continues to use a figure called “Socrates” as his principal interlocutor, and in this way he creates a sense of continuity between the methods, insights, and ideals of the historical Socrates and the new Socrates who has now become a vehicle for the articulation of his own new philosophical outlook. In doing so, he acknowledges his intellectual debt to his teacher and appropriates for his own purposes the extraordinary prestige of the man who was the wisest of his time.