In Open Book, Acconci's open mouth fills the screen. Struggling to hold his mouth open, he attempts to talk to the viewer, intoning in an almost unintelligible voice: "I'm not closed, I'm open. Come in... You can do anything with me. Come in. I won't stop you. I can't close you off. I won't close you in, I won't trap you. It's not a trap." As though under the authority of an implicit contract with the viewer, Acconci fights to keep his "promise" of remaining open. When his mouth accidentally closes, he begs for the viewer's forgiveness: "That was a mistake. I won't close. I won't close you off. I won't close you in. I'm open to everything..." The controlled action is typical of the works in which Acconci sets up an implicit agreement to perform a specific act for the viewer.