If I say that my somewhat extravagant imagination yielded simultaneous pictures of an octopus, a dragon, and a human caricature, I shall not be unfaithful to the spirit of the thing. A pulpy, tentacled head surmounted a grotesque and scaly body with rudimentary wings; but it was the general outline of the whole which made it most shockingly frightful.
This quotation from Section I offers the first description of Cthulhu as it appears on Wilcox’s clay bas-relief. In addition to giving both Thurston and the reader a visual to associate with the monster, the way in which Thurston describes it also emphasizes the idea that Cthulhu exists beyond the laws of nature. He attempts to define it in terms of creatures that humans can conceptualize like octopuses and dragons, but even these images do not do Cthulhu justice. The general impression of it is, in Thurston’s words, “shockingly frightful” because of how it defies logic and reason.
There then followed an exhaustive comparison of details, and a moment of really awed silence when both detective and scientist agreed on the virtual identity of the phrase common to two hellish rituals so many worlds of distance apart. What, in substance, both the Esquimau wizards and the Louisiana swamp-priests had chanted to their kindred idols was something very like this… “Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn.”
In Section II, the reader learns of an American Archeological Society meeting at which Inspector Legrasse and a scholar from Princeton University, Professor Webb, realize that they both engaged with the same strange cult in different parts of the world. This detail propels the plot forward as it emphasizes that Cthulhu’s worshippers are not limited to one physical location or culture. Instead, they represent a wide-reaching movement, information which significantly expands the scope of Professor Angell’s research. He goes on to collect stories from people around the world who were affected in some way by either the cult or bizarre dreams.
If heaven ever wishes to grant me a boon, it will be a total effacing of the results of a mere chance which fixed my eye on a certain stray piece of shelf-paper. It was nothing on which I would naturally have stumbled in the course of my daily round, for it was an old number of an Australian journal, the Sydney Bulletin for April 18, 1925.
This quotation comes from the beginning of Section III and marks Thurston’s return to researching the Cthulhu cult. He admits that he had largely given up his attempts to find answers, but coincidentally catching sight of an old news article that mentions a strange idol found at sea pulls him back in. Signifying the influence of fate, Thurston’s discovery of Johansen’s story puts him on the path to discovering the truth about Cthulhu and its inescapable influence over humanity.
Persuading the widow that my connexion with her husband’s “technical matters” was sufficient to entitle me to his manuscript, I bore the document away and began to read it on the London boat. It was a simple, rambling thing—a naive sailor’s effort at a post-facto diary—and strove to recall day by day that last awful voyage.
After reading of Johansen’s ill-fated voyage in Section III, Thurston travels to Oslo where he persuades Johansen’s widow to grant him access to her husband’s final manuscript. She is unaware of its contents when she hands it over to Thurston, and what he finds is the final details that convince him of Cthulhu’s existence and the existential threat it poses to mankind. Reading Johansen’s firsthand account of his ship’s encounter with R’lyeh and Cthulhu makes it impossible for Thurston to turn back, marking the climax of the story. From this point on, his fate is effectively sealed because he knows too much.