Complex sentence: Mina "Margery" Crandon (1888-1941) was the wife of a wealthy Boston surgeon and socialite, Dr. Le Roi Goddard Crandon, and she became well known as a medium who claimed that she channeled through her dead brother, Walter Stinson.
Split into simpler sentences: Mina "Margery" Crandon (1888--1941) was the wife of a wealthy Boston surgeon and socialite, Dr. Le Roi Goddard Crandon. She became well known as a medium who claimed that she channeled through her dead brother, Walter Stinson.