The emphasis on letters and language rather than what's actually being said immediately calls to mind McLuhan. There's that older guy running the archaeological digs who says he doesn't care what's actually being communicated on the stones he finds because it's usually just bookkeeping and what's really important to him is the letters themselves, the shape of them, how they were carved.
I've read a few interviews with DeLillo where he's said that was something which took hold of his writing from The Names onward. He's since paid particularly close attention to how the letters look on the page and chooses words and sentences accordingly.
en.wikipedia.org
"What do you find on the stones, Owen, that's so intriguing?"
He stretched his body, easing into an answer.
"At first, years ago, I think it was mainly a question of history and philology. The stones spoke. It was a form of conversation with ancient people. It was also riddle-solving to a certain degree. To decipher, to uncover secrets, to trace the geography of language in a sense. In my current infatuation I think I've abandoned scholarship and much of the interest I once had in earlier cultures. What the stones say, after all, is often routine stuff. Inventories, land sale contracts, grain payments, records of commodities, so many cows, so many sheep. I'm not an expert on the origin of writing but it seems to be the case that the first writing was motivated by a desire to keep accounts. Palace accounts, temple accounts. Bookkeeping."
"And now?"
"Now I've begun to see a mysterious importance in the letters as such, the blocks of characters. The tablet at Ras Shamrah said nothing. It was inscribed with the alphabet itself. I find this is all I want to know about the people who lived there. The shapes of their letters and the material they used. Fire-hardened clay, dense black basalt, marble with a ferrous content. These things I lay my hands against, feel where the words have been cut. And the eye takes in those beautiful shapes. So strange and reawakening. It goes deeper than conversations, riddles."