Ma’aseh Berashith, Hebrew “Work of Creation,” is one of the oldest branches of Jewish mysticism, which consists of theory and practice based on the account of Creation of the world found in the Book of Genesis. Currently little is known of the system except scholars believe that the Sepher Yetzirah was a text of this school. Much of the lore of the Ma’aseh Berashith was absorbed into the Kabbalah. A.G.H.
Greer, John Michael. The New Encyclopedia of the Occult. St. Paul, MN, Llewellyn Worldwide. p. 285.