Back to Methuselah (A Metabiological Pentateuch) is a 1921 series of five plays and a preface by George Bernard Shaw. The five plays are:

In the Beginning: B.C. 4004 (In the Garden of Eden); The Gospel of the Brothers Barnabas: Present Day; The Thing Happens: A.D. 2170; Tragedy of an Elderly Gentleman: A.D. 3000; As Far as Thought Can Reach: A.D. 31,920

The plays were published with a preface titled The Infidel Half Century, and first performed in 1922 by the New York Theatre Guild at the Garrick Theatre.