For example, in The Music of Erich Zann, the protagonist befriends a violinist who lives the floor above him — but who plays violent, crazy arias, the sounds of which are deeply unsettling. Why so unsettling? Well, the narrator can’t quite say. The music is …

… a pandemonium which would lead me to doubt my own shaking sanity”, he notes. “It was not that the sounds were hideous, for they were not; but that they held vibrations suggesting nothing on this globe of earth, and that at certain intervals they assumed a symphonic quality which I could hardly conceive is produced by one player.”

As the story reaches its climax, he writes that “the frantic playing had become a blind, mechanical, unrecognizable orgy that no pen could ever suggest.” Magnificent: The pen cannot even suggest a description!

A 1980 short film based on “The Music of Erich Zann”.

Lovecraft pulls a similar ploy in Pickman’s Model, in which the protagonist befriends a painter who apparently specializes in creating ultra-creepy works. But when the narrator is finally ushered into the painter’s gallery to behold the stuff, language evaporates. “There’s no use in my trying to tell you what they were like,” he says, “because the awful, the blasphemous horror, and the unbelievable loathesomeness and moral foetor came from simple touches quite beyond the power of words to classify.”

Often, Lovecraft deals out these “I can’t even” moments with rather dry humor, as in The Color Out of Space—in which a farm and its surrounding countryside are being slowly deformed by an alien force. Neighborhood children catch a woodchuck, and “the proportions of his body seemed slightly altered in a queer way impossible to describe, while its face had taken on an expression which no one ever saw in a woodchuck before.” (Those inexplicable facial expressions of woodchucks.) Then plants begin to grow oddly: “Never were things of such size before, and they held strange colours that could not be put into any words.” And of the insects, yikes, what can be said? “Most of the creature seemed not quite usual in their aspects and motions, and their nocturnal habits contradicted all former experience.”

The issue that debuted Lovecraft’s short story “Herbert West: Reanimator”.

Lovecraft’s tour-de-force of losing the ability to can is probably At the Mountain of Madness. It’s a sprawling novella in which a pair of Antarctic adventurers explore the ruins of a massive city created by the cosmos-born Old Ones. A huge chunk of the book is simply them parsing the architecture and bodies of a few dead Old Ones and piecing together the backstory of the race, but every few paragraphs the narrator confesses he just totally cannot describe the epic strangeness at hand. “Existing biology would have to be wholly revised, for this thing was no product of any cell-growth science knows about,” he notes as he conducts an autopsy on an Old One. Their evolution is “utterly beyond our powers of speculation”; the creatures “probably have more than five senses, so that its habits could not be predicted from any existing analogy.” As they go deeper into the city and the architecture gets even more disturbing, the explorers stop sending messages back to camp—and thus to newspapers back home—because “our sensations could not be conveyed in any words the press would understand”. As they discover the “insane graves” of the Old Ones and ponder their dread meaning, he and his partner “harbored wild guesses which sanity forbade him to formulate completely.”

In the final moments of the story, they’re chased by a Shoggoth, a sort of glutenous, protoplasmic monster used as a slave in ancient times by the Old Ones. The narrator is, for once, able to describe the beast fairly accurately:

“The nightmare plastic column of foetid black iridescence oozed tightly onward through its fifteen-foot sinus; gathering unholy speed and driving before it a spiral, re-thickening cloud of the pallid abyss-vapour. It was a terrible, indescribable thing vaster than any subway train — a shapeless congeries of protoplasmic bubbles, faintly self-luminous, and with myriads of temporary eyes forming and unforming as pustules of greenish light all over the tunnel-filling front that bore down upon us …”

This was a sufficiently clear description that the artist for the cover of Astounding Stories, February 1936, drew a picture:

Not quite so terrifying when it’s turned into a watercolor, really.

But the emotional impact of beholding this beast? The internal deformations of one’s very soul? That remains beyond sanity, beyond language, beyond vowels and syllables! “I might as well be frank—even if I cannot bear to be quite direct—in stating what we saw; but with the time we felt that it was not to be admitted even to each other,” the narrator continues. “The words reaching the reader can never even suggest the awfulness of the sight itself. It crippled our consciousness so completely that I wonder we had the residual sense to dim our torches as planned, and to strike the right tunnel toward the dead city.” They ran like hell, and while the main narrator emerges from the experience traumatized but coherent, his companion is transformed permanently into a babbling, laughing lunatic.