The story of "Eugene Onegin" was written by Alexander Pushkin. He was Russia’s most famous writer and Tchaikovsky made several of his stories into operas. He was careful not to make the opera too long, and chose several chapters from Pushkin’s original book so that the story sometimes jumps from one time to a time much later. Russian operas are quite often like this: they are a series of “tableaux”, i.e. scenes from a story. Sometimes the audience has to imagine what happens between the acts.