There are such things as bacteria. Sometimes they get established in our system and cause us disease. We live in a dynamic universe and sometimes events are to our benefit and at other times to our detriment. That's the way the world is. Buddhism is not concerned with explaining why this is so, it simply makes the common sense assertion that the universe is dukkha (suffering) sometimes at odds with our dreams, our wishes and our desires. What Buddhism is concerned with is teaching us to modify our desires so we are less likely to be in conflict with the way things are and how to remain calm and content when they do conflict with the way things are.”
- S. Dhammika