Thurston is a unique character in that the reader knows of his fate long before he does. By identifying him as deceased in the first lines of the story, Lovecraft is able to focus the narrative on how and why Thurston reaches his untimely end rather than giving the reader the opportunity to wonder how his journey might conclude. This definitive approach emphasizes the idea that the universe contains forces that exist beyond humankind’s knowledge or control. Thurston may have the ability to seek answers on his own terms, but once he pieces together the mystery of Cthulhu, his fate becomes inescapable. The journey that he goes on throughout the story further emphasizes the powerlessness of man and the limitations of a rational mind. When Thurston first uncovers hints of Cthulhu among Professor Angell’s belongings, he is determined to make sense of the sculpture and stories that seemed to disturb his grand-uncle during his final days. He takes a very scientific approach, analyzing evidence from Professor Angell’s papers and conducting additional research on his own. This method emphasizes Thurston’s initial belief that he can solve the mystery of Wilcox’s bas-relief through logical reasoning.
As Thurston continues to learn about the Cthulhu cult, however, his commitment to rationalism dissipates, and he comes to realize just how expansive and unknowable the universe truly is. The tales of Wilcox and Legrasse begin pushing Thurston toward this conclusion, but Johansen’s manuscript is what really opens his eyes. His unfiltered, terror-filled account of his arrival at R’lyeh and encounter with Cthulhu itself, both of which defy all laws of nature, convince Thurston of the legend’s legitimacy. Once he acknowledges these dark and disturbing aspects of the cosmos, he loses his sanity as dreams of Cthulhu and the Great Old Ones haunt him. This cognitive downfall, which ends with his death, highlights the great cost of knowledge and the importance of mankind’s ignorance. Thurston himself even acknowledges that he is likely to die because of the secrets he uncovered. In the end, he seems to regret his curiosity and prays that no one else will endure the psychological torment that his quest for answers has brought upon him.