I grabbed this off some web page. READ ALL OF IT. It might help and explain better. I think it gives a few examples.
Soap"With enough soap, we could blow up just about anything."
'Tyler was full of useful information.'
-Tyler and the Narrator
Erika writes: When the narrator first meets Tyler, Tyler declares that he is a soap salesman, although Tyler has various other occupations including a night-time movie projectionist and a waiter. Tyler, however, most identifies himself with the job of selling soap, thus lending weight to the symbolic importance played by soap in the movie. Tyler calls soap "the foundation of civilization" and tells the narrator that "the first soap was made from the ashes of heroes". He also uses lye, a chemical ingredient of soap, to introduce the narrator to the pain of "premature enlightenment." In this role, soap is a symbol of purification and cleanliness, of a culture lacking the hypocrisy and fraudulence of contemporary culture. However, in that Tyler makes soap by stealing fat from the liposuction clinic dumpsters and then sells these soaps "to department stores for $20 a bar", soap also represents a too highly refined culture, a culture where all traces of natural humanity are suppressed, effaced, washed off. Rather than being made from the "ashes of heroes", soap is made from "selling rich women their own fat asses." The fact that Tyler is a salesman for this product represents Jack's subservience to this culture. Fight Club is founded as a way for men to regain their primitive instinct that culture tries to wash off. In that soap represents both the purifying and effacing tendencies of civilization, its symbolic function resembles that of ice in The Mosquito Coast where Allie Fox, a man obsessed with the fact that American civilization has become effete, perfects an ice machine believing ice to be the foundation of civilization.