Final answer:
Fitzgerald's use of 'stuff' in line 140 captures the unique complexities of Gatsby's character. The direct address and flash forward emphasize his individual story rather than a general archetype, and the section break indicates a narrative shift in the story.
Step-by-step explanation:
In the context of line 140 from F. Scott Fitzgerald's work, 'stuff' refers to the intricate details and the complex nature of Gatsby's life and character. Fitzgerald uses direct address and flash forward to highlight that, despite any parallels drawn between Gatsby and other figures of the 1920s, his narrative is distinctly personal and not meant to serve as an archetype. The direct address implicates the reader, establishing a connection that brings one into the fold of the story with a sense of immediacy. A flash forward provides a glimpse into the outcome of the story, suggesting a predetermined fate for Gatsby that the reader is powerless to alter. The section break signals a narrative shift, often indicating a change in time, setting, or perspective, which is a common device in modernist literature to juxtapose different elements of a story and highlight their contrasts.