Upon first read, Act I may seem random and irrelevant to the rest of the play. In fact, though, this Act allows the audience a believable situation in which to meet all the main characters in the play. Since Shaw is dealing with social classes, highlighting the differences between them (both actual and stereotypical), his characters wouldn't typically interact in society. Yet, he needs them to meet and intrigue each other in order for the rest of the play to "work". So, the rain storm creates a situation that causes people of all stations to gather in the same spot, shelter from the rain, and forces them to interact. Beyond this reason, Act I gives the audience insight into the characters themselves. We understand the changes in Higgins and Eliza more clearly, because we see them unguarded in Act I. We understand the irony of Fredddy's infatuation with Eliza better because of this Act. We expect Pickering's care and concern for Eliza throughout the "experiment" because of Act I. Shaw uses Act I as a catalyst for characterization, theme, and irony in his play.