 Gurdjieff classified plants as having one brain, animals two and humans three brains.In "Beelzebub's Tales to His Grandson", Gurdjieff greatly expanded his idea of humans as "three brained beings".In the book "The Fourth Way", Ouspensky refers to the "center of gravity" as being a center which different people primarily operate from (intellectuals, artists, and sports enthusiasts, for example, might represent each of these centers).