This book, which Skinner often call his most important work, extends the laboratory-based principles of selection by consequences to account for what people say, write, gesture, and think. Skinner argues that verbal behavior requires a separate analysis because it does not operate on the environment directly, but rather through the behavior of other peoples in a verbal community. He illustrates his thesis with examples from literature, the arts, and the sciences, as well as from his own verbal behavior and that of his colleagues and children.