The poets were not the only target of Plato's attack.  The sophists were criticized mercilessly by Socrates.  These wandering teachers were the successors of the rhapsodes.  Recently discovered fragments from the fifth and fourth centuries B.C.E. prove that they were also heirs of the tradition started by the poet Simonides (556 - 468 B.C.E.).^[1]  These few surviving documents have allowed scholars to trace the line of descent from poet to rhapsode to sophist as part of the transition from oral tradition to written record.  When material from more than one source was put together, interpreters were needed to translate anachronistic expressions and foreign words.^[2]  As the epics came to be preserved in written collections, a group of rhapsodes became interpreters as well as presenters of poetry.  Some of the earliest prose consists of their efforts to explain the meaning of traditional names and phrases in the old theogonies.  Glosses, along with explanations of Homeric proper names and obscure words by "etymology," were developed, collected and transmitted by the rhapsodes.^[3]  Over time, they began to offer instruction in the interpretation of poetry, in the use of letters, as well as in the classifications and definitions laid down by their predecessors.  They also taught techniques of oral presentation and public speaking in addition to the use of an "art of memory," which was said to have been invented by Simonides.^[4]  At some point, the most prominent of their number became known as teachers of wisdom.  The early sophists wandered all over the Greek-speaking world.  Later, they converged on Athens, the leading democratic city-state, where they could establish themselves as professional educators and gather their best students around them.  A number of Plato's dialogues bear the names of the major sophists in the tradition - Gorgias, Protagoras, Critias and Hippias.  For instance, at Protagoras 339a, there begins an extended passage in which the sophist explains a lyric poem by Simonides so as to rationalize some of its contradictions.  The Sophist offers a number of different definitions and classifies sophists themselves as "deceptive image makers."  The Gorgias contains an extended critique of sophistic deceptions, and in the Greater Hippias 285b-286a and the Lesser Hippias 368c-369a, Socrates takes an ironic tone in praising Hippias's use of the memory "art."  

The major contribution to our understanding of the Simonidean tradition came from Frances A. Yates, an historian of the Renaissance.  She demonstrated that by about 500 B.C.E., the ancient Greek orators and sophists were making use of a mnemonic technology that grew out of the formulaic system of the poetic tradition.  This was the "art of memory" invented by Simonides.  It was based on a technique of impressing on the mind a series of "places" and "images" (τόπoι and εικόvες in Greek, whence our words "topics" and "icons").^[5]  Knowledge of this system was passed on to the Romans (the method of loci and imagines in Latin).  It came down through the European tradition as a part of rhetoric, and also as a branch of ethics, where it was organized around a scheme of virtues and vices.  The technology for remembering involved mentally picturing a spatial structure - such as a theater, a building, a park, or a geometric figure - as the background "places."  This scheme was then used as the representational format for encoding information into memory.  Items to be remembered were converted into mental images and then set into the "places" in this imagined background.  While the ancient orator gave his speech, he walked through the background space in his imagination, visiting each of the places in turn, re-collecting the images he had set in them.  By this system, he was able to deliver long speeches from memory with complete accuracy.  Since the images were placed in the background in a series, the speaker was able to move in his or her imagination either forward or backward from the place selected as a starting point.  Numerical markers were set into the background regions at regular intervals to ensure that the speaker would not lose his place.  According to a memory treatise, the art of memory was like inscribing "words in the soul."  The backgrounds were compared to wax tablets, the images to letters, the order and arrangement of the images to the writing, and the presentation to the reading (Ad Herennium III. XVII. 28-29).  The backgrounds, like wax tablets, were lasting but the images, like letters, were effaced when no further use was made of them. 

Yates showed that the education provided by the sophists - so harshly criticized by Plato - made extensive use of this mnemonotechnic to memorize names or specific terms.  Words were broken down into their etymological roots and each component was matched to an image of something that sounded similar.^[6]  She said that the etymological use of the mnemonic may have been an attempt to adapt an oral technology to writing (230).  Evidence from a memory treatise attributed to the sophist Hippias of Elis (who appears as chief interlocutor in Plato's Lesser Hippias and Greater Hippias), indicates that the education he offered involved committing to memory vast quantities of etymological information.  Yates suggested that it was possible that Plato=s objection to these highly paid wandering teachers might be explained by this sophist memory treatise with its senseless use of such etymologies.  According to Yates, "One would expect a Platonic memory to be organized not in the trivial manner of such mnemonotechnics, but in relation to the realities" (51).

Yates also described a branch of the memory tradition that rejected the use of images and imagination, relying instead on the principles of division and orderly arrangement.  This method, later called "dialectic," grew out of the observation that "thoughts" and certain "parts of speech," do not call up images in the same way as material things (Quintilian Institutio Oratoria XI. ii. 24-26).  The technique involved dividing the material to be remembered into manageable "lengths" which were then organized into a schematic "in which the more general or inclusive aspects of the subject came first, descending thence through a series of dichotomized classifications" to subdivisions containing more specialized, or individual aspects (230).  In contrast to the method which impressed material on memory by envisaging vivid and emotionally charged "images," the method of memorizing by "dividing and composing" stressed the use of cool analytic thought processes in the continuous rehearsal and recitation of the abstract order of the "divisions."