From F. A. Wolf’s Prolegomena ad Homerum section XX:

“Now there is not only no evidence or even whisper of [epistles] in Homer and no indication at all of even the most tenuous beginnings of institutionalized writing or that “gift of Cadmus” but—and this is clearly the most significant piece—only contradictory evidence. The word for ‘book’ is nowhere; a word for writing is nowhere; mention of letters is nowhere.

In so many thousands of lines there is nothing about reading while everything is set up for hearing. There are no contracts or treaties except in person; there is no source for stories from earlier days except for memory, rumor and uninscribed monuments. We find the repeated and, in the Iliad, diligent, invocation of the Muses, the goddesses of Memory. No title is inscribed on pillars and tombs which are often mentioned.

There is no other kind of inscription at all: we don’t find stamped coin or fabricated money; there’s no use of writing in domestic affairs and trade; there are no written or drawn maps; and, finally, there are no couriers or letters. If these had been customary in Odysseus’ homeland or if “folded tablets”* had been available to the inquiries of the suitors and Telemachus, we probably would have a much shorter Odyssey or, as Rousseau decided, we wouldn’t have any Odyssey at all!”

Iam vero non modo nullum tale in Homero exstat testimonium rei vel vestigium, nullum ne tenuissimorum quidem initiorum legitimae scripturae vel Cadmei muneris indicium, sed, quod longe maximi momenti est, contraria etiam omnia. Nusquam vocabulum libri nusquam scribendi nusquam lectio-fiis nusquam letterarum: nihil in tot millibus versuum adlectionem, omnia ad auditionem comparata; nulla pacta aut foedera nisi coram; nullus veterum rerum famae fons prae-ter memoriam et famam et illitterata monumenta. eo Musarum, memorum dearum, diligens et in Iliade enixe repetita invocatio; nullius incippis et sepulcris, quae interdum memorantur, titulus; non alia ulla inscriptio; non aes signatum aut facta pecunia; nullus usus scripti in rebus domesticis et mercatura; nullae geographicae tabulae; denique nulli tabellarii, nullae epistolae, quarum si consuetudo fuisset in patria Ulyssis, vel si percontationibus procorum et Telemachi suffecissent, procul dubio Odysseam aliquot libris breviorem, aut, ut Roussavius coniiciebat, omnino nullam haberemus.

*A reference to the only indication of writing in Homer, coming from Glaukos’ speech to Diomedes when he describes Bellerophon as sent to Lykia by Proitos with a “folded tablet” (6.168-170):

“He sent him to Lykia, and he gave him murderous signs
Which he wrote on a folded tabled, many heart-rending things,
In which he ordered his father-in-law to welcome him in order to kill him.”

πέμπε δέ μιν Λυκίην δέ, πόρεν δ’ ὅ γε σήματα λυγρὰ
γράψας ἐν πίνακι πτυκτῷ θυμοφθόρα πολλά,
δεῖξαι δ’ ἠνώγειν ᾧ πενθερῷ ὄφρ’ ἀπόλοιτο.