Putting aside Buddha's stories which have similar happenings but this is what I experienced myself.
One night I was having dinner with a group of friends in a private room. There is this full glass wall to ground window which we can look into a garden. As the sun sets, it got darker outside and the warm light in our room attracted some insects and reptiles.
As we were waiting for our food and everyone were excited exchanging greetings, someone suddenly said "oh dear! look at that lizard, it is going to eat the moth!". All of us ran over to the glass window and with all the knockings tried to shoo the lizard off. Our compassion at work so the reaction is natural. When all the shooing were going on, I was watching and it suddenly occurred to me...
".... the lizard was trying to take a meal, the moth was there and so became the bait. We were all trying to save the moth....what about the hungry lizard? Isn't the lizard also worthy of our compassion? What is the lizard going to eat? If the lizard did not eat the moth, the lizard will eat some other insects, so where is our compassion for the other insects?"
Do you have an answer?
This World is a cycle. Things happened for a reason. It is the natural eco system that World depends upon. We are part of this cycle because we are in the same realm as all other animals, insects and others. The only different is we are in different forms. Everything depend on each other to recycle. One is gone another will appear and it goes on.
There is another story that goes like this...
A boatman pushed the boat out to the river. In the course of the pushing, the boat slides over mud. On the boat there was a Monk and many other lay people. One man walked up to the Monk and asked "Shifu (meaning venerable master), did this boatman committed sin while pushing the boat out from shore to the river. In this pushing the boat slides over mud killing many creatures living in the mud?" Shifu looked at the person who asked the question and said "you are the one that have committed the sin, not the boatman". The person was shocked! The Monk further explained "The boatman is doing his work and he has no intention to kill. If you did not get on the boat, the boatman need not move the boat and therefore no lives were killed. Killing is completed with intention and you think about these creatures being killed. No one on this boat thought about it".
Therefore many happenings are Cause and Effect of our actions. Did you get it????