Albert was an ordinary worker in an oil company in America. His workmates gave a nickname  "Four dollars a bucket  " to him, for he was always used to leaving an advertisement of his company "Four dollars a bucket of oil" below his name whenever and wherever he wrote down his name. As time went by, people forgot his real name. Later, when Rockefeller, the board chairman of the oil company, heard of it, he was very surprised, so he invited Albert to come to his office. "Some people give you a nickname for 'Four dollars a bucket'. Why aren't you angry?" asked Rockefeller with some puzzlement in his eyes. "Oh! Mr. Rockefeller! I like this nickname very much, because 'Four dollars a bucket' is our company's advertisement. As long as someone calls me 'Four dollars a bucket' once, I think it's a free advertisement for our company. I have no reason to get angry. Don't you think so, Mr. Rockefeller?" "Oh! What a fantastic man!" Rockefeller said excitedly when hearing Albert's words. "Young man, work harder! You must succeed in the future! I believe in you!" Five years later, Albert became the second board chairman after Rockefeller. Later Albert said in one of his reports, "I don't think we should feel frustrated when we have no way to do the world-shaking things. We should treat every thing actively because maybe our future success will begin from a small thing!" What is the main idea of this passage?
It's very important to do small things well. Rockefeller asked young people to work harder. You can't get angry when someone calls your nickname. You should make more advertisements for your company.