John Marcher often describes his fate in hyperbolic terms. When May asks whether "it's to be something [he'd] merely suffer" in Chapter 1, he responds:
Well, say to wait for—to have to meet, to face, to see suddenly break out in my life; possibly destroying all further consciousness, possibly annihilating me; possibly, on the other hand, only altering everything, striking at the root of all my world and leaving me to the consequences, however they shape themselves.
Hyperbolic phrases include "destroying all further consciousness," "annihilating me," "altering everything," and "striking at the root of all my world." These phrases seem disingenuous, but soon the sincerity of Marcher's words becomes clear. He is so nervous about his fate that he actually believes these grandiose phrases.
In this passage, Marcher also makes repeated use of superlatives like "all" and "everything," which reinforce the all-encompassing nature of the idea of fate. Despite the fact that Marcher had previously forgotten his fate, he takes up the idea with great fervor after May reminds him of it. He even begins to believe that his fate will impact everything in his life, and that his entire existence rests on this great unknown (which he also terms "the Beast"). In the end, despite his ultimately anticlimactic fate, he ends up deeply shaken and regretful in a way that does, in fact, "strik[e] at the root of all [his] world": he realizes he has lost the woman he could have loved.
