the yellow brick road symbolises the journey of what the crew are trying to achieve which leads the to good and is a simple path to take to success. the yellow brick road is a big part of the book as it symbolises there journey to the emerald city. they were lucky enough to have this road lead the whole way to the emerald city which really set up the whole story.
when Dorothy was set of on the yellow brick road there was also a red brick road which kinda creates a bit of a mystery and would lead to probably the darker side of oz, so where does that take you. in conclusion the whole story can create a bit of confusion as we are never told a lot about the actual land of oz