What does Fog/ Smoke represent?

After her brother, Warren, tragically died, and her parents shunned her from his funeral, the six month pregnant Mia Wright abandoned her post as a surrogate mother to the Ryans and fled to San Francisco to have the baby as her own. For the three months she waited for Pearl's arrival, "Mia walked the city, circling the lagoon...climbing...crossing the Golden Gate...in a fog do dense, she could hear, but not see, traffic rushing alongside her. The fog mirrored her state of mind so perfectly she felt as if she were walking through her own brain: a haze of formless, pervasive emotion..." (231). The fog is the mystery ahead. It represents the unknown, and like the smoke produced from the little fires in Chapter 1, the fog symbolizes confusion, transition, and clarity once it clears.