Brian thinks to himself, ' So fast. So fast things change."What causes him to think this?

There could be various reasons that cause Brian to think, "So fast. So fast things change." Some possible reasons could include:

1. Personal experiences: Brian might have recently gone through significant changes in his life, such as a breakup, loss of a job, or a move to a new city. These experiences could make him reflect on how quickly things can change.

2. Observing others: Brian might have witnessed someone close to him going through unexpected changes, such as a friend losing a loved one or a family member experiencing a sudden illness. This observation could make him realize the unpredictable nature of life.

3. News or current events: Brian might have been exposed to news stories or events that highlight rapid changes happening in the world, such as political upheavals, natural disasters, or technological advancements. These external factors could make him contemplate the speed at which things can change.

4. Aging or personal growth: Brian might be at a stage in his life where he is reflecting on the passage of time and how it has brought about changes in himself and his surroundings. This introspection could lead him to think about the rapidity of change.

5. Philosophical or existential pondering: Brian might be engaging in deep thoughts about the nature of existence, impermanence, or the concept of time. These philosophical musings could prompt him to contemplate the swift pace at which things can transform.