Everything that happens follows a causal chain stretching back infinitely. Everything that ever happened had to happen, everything that is happening has to be happening and everything that will happen has to happen. There are no mistakes in nature/God. Even kids getting cancer and people getting tortured and killed by serial killers are events that had to happen following a logical chain of events from the beginning of time up to that point. There are no mistakes, even the thing that we percieve as ugly or bad have a reason for existing or happening.