Chaos theory is the science of the unpredictable. It is the study of dynamic systems that are extremely sensitive to initial conditions – this effect is commonly known as the butterfly effect. The theory is that miniscule changes in initial conditions can have dramatically different effects on the outcome – hence the idea that a butterfly flapping its wings in a Brazilian jungle can trigger a tornado in Texas.
I have my own theory that this can also be applied to business referrals. Consider your biggest client, and the chain of small events that brought them to you.