I am walking on a street. A tall man with white hair addresses me and asks for help. He can't see in this bright sunlight and needs someone to guide him to the next bus station. I agree to help him. While walking together he tells me that a young man around 18 had promised him yesterday to come to help but he didn't showed up. I answer that I have a son of this age and he is also often promising but then forgets to do it...