When two things occur successively we call them cause and effect if we believe one event made the other one happen. If we think one event is the response to the other, we call it a reaction. If we feel that the two incidents are not related, we call it a mere coincidence. If we think someone deserved what happened, we call it retribution or reward, depending on whether the event was negative or positive for the recipient. If we cannot find a reason for the two events' occurring simultaneously or in close proximity, we call it an accident. Therefore, how we explain coincidences depends on how we see the world. Is everything connected, so that events create resonances like ripples across a net? Or do things merely co-occur and we give meaning to these co-occurrences based on our belief system? Lieh-tzu's answer: It's all in how you think.
Liezi Lieh-tzu: A Taoist Guide to Practical Living