Janusian thinking—"actively conceiving two or more opposite or antithetical ideas, concepts, or images simultaneously," according to the author's definition—is proposed as a specific thought process that operates in the act of creation. The author uses the symbolic elements in Eugene O'Neill's The Iceman Cometh to illustrate the essence of simultaneous contradiction in the different structures of the play. This is supported by evidence from Oriental religions, modern music, architecture, and scientific discoveries. Janusian thinking is not solely responsible for the act of creativity, but it is a crucially important factor in diverse types of the creative process and the first specific thought process in creativity to be defined.