The younger of two sons tells the story of a mistake he made that changed the course of humanity forever. He tells of his childhood, and of his laziness and general lack of effort in life. He tells of his hard working older brother who for many years was the pride of the family and the provider of the food.
One day, when the younger son asks, the elder son tries to explain the need to sacrifice. He explains that you have to sacrifice the best of what you have, as a sign of respect. The younger sees it as a contest, a test of who can sacrifice more. When luck eventually favors him despite his lack of effort, and his brother has a tough time with the crops that year, he gloats over his good fortune and proudly makes a huge sacrifice. Soon after he makes a mistake that changes the world forever.
A little bit of seemingly harmless gloating can set off unstoppable chains of catastrophes. The mistake of one individual can ruin lives for thousands of generations.
I think if I could live my life over again this would be a better world today dwelt in by happier people -- for I think I would not have commited the folly of my youth, the folly that has drawn the lines for conflict and suffering that you are heir to now."