Socrates says that they must finally turn to the subject of “propriety and impropriety in writing.” He tells Phaedrus an Egyptian myth he’s heard. A certain god named Theuth discovered various things, such as numbers, geometry, astronomy, and ultimately letters. Theuth presented his findings to King Thamus of Egypt, explaining the various benefits each would bring to the people. When he introduced letters, Theuth claimed that these would serve as “an elixir of memory and wisdom.”
Having covered the topic of how to speak well, now they turn to a discussion of writing. As he’s done before, Socrates uses an illustrative myth to make a point about the utility of letters. In this case, letters are presented as an exciting technological innovation.
Socrates continues the story: King Thamus told Theuth that Theuth’s affection for letters had led him astray; letters actually have the opposite effect, “[producing] forgetfulness in the souls of those who have learned it.” This is because people begin to rely on letters instead of really internalizing what they’ve learned. Writing is thus not actually an elixir of memory, but merely of reminding.
Thamus goes on to explain that one who relies on writing will appear to have wisdom in the eyes of his students, but will lack the reality of it. His students will hear many things from him without actually having been taught them. They’ll appear to know much themselves, but will actually know nothing. This will make them “difficult to get along with because they have acquired the appearance of wisdom instead of wisdom itself.”
Because one hasn’t actually learned the things he has read, he’s able to look wise, while actually lacking knowledge all the while. He passes this same deficit, and the corresponding moral weakness, along to his students.
Socrates and Phaedrus talk about this story and its implications. Socrates remarks that writing has a strange resemblance to painting—that is, the figures in paintings look as if they are alive, but they stand silently if questioned. Similarly, one cannot question letters; they signify the same thing at all times. Furthermore, a written text has no ability to differently address those who are experts and those who are ignorant. It also can’t defend itself if unjustly abused.
Socrates says there’s a better kind of speech—that which is “written together with knowledge in the soul of the learner.” Such speech knows how to defend itself, when to speak, and when to keep silent. Phaedrus recognizes that Socrates is talking about “the living, animate speech of the man who knows, of which written speech would rightly be called a kind of phantom.”
Socrates is speaking of dialectic—the interactive process by which a philosopher and his interlocutor arrive at truth. This type of speech has none of the liabilities of the written word, which is little better than an echo of it.
Socrates compares the science of dialectic to farming—it takes “a fitting soul, plants and sows in it words accompanied by knowledge, which are sufficient to help themselves and the one who planted them.” The seed so planted can even flourish unto immortality and bring a person the greatest possible happiness.
Socrates emphasizes the living, organic character of dialectic, which is carefully planted and nurtured in a specific soul known to the teacher—something writing can’t achieve. Dialectic has endless potential, because it helps someone along the path toward a philosophical life and the freedom of the soul.
As Socrates and Phaedrus wrap up their conversation, Socrates remarks that he thinks Isocrates will turn out better than Lysias, since Isocrates demonstrates “an innate philosophical instinct” which Lysias lacks. The two pray to the gods of the place, that they will be made beautiful within, and they depart from the riverbank.
Isocrates was a contemporary of Plato’s, known as a brilliant rhetorician and writer of speeches. Readers of Plato would likely have been familiar with his renown, and Socrates’s remarks are perhaps meant to show that Plato isn’t criticizing Isocrates wholesale. The two close their discussion of good and bad speech with prayer and then leave together.