tl;dr:Writing a novel is actually similar to writing quality code - "sentences must be well written, but the overall structure and relationship between parts is crucial." A novel is immutable whereas code evolves over time, and is an endless stream of changes. Salvatore's hypothesis is that the initial design of the novel will greatly inform what happen later.
tl;dr:"Writing comments is of paramount importance in order to produce good code" for two reasons. (1) Comments explain why the code exists and is performing a specific action. (2) It's a tool for lowering the cognitive load of the reader.