Harriet Scott Chessman takes us into the world of Mary Cassatt's early impressionist paintings Through Mary's sister lydia, whom the author sees As Cassatt's most inspiring muse. Chessman hauntingly brings to life Paris ...Harriet Scott Chessman takes us into the world of Mary Cassatt's early impressionist paintings Through Mary's sister lydia, whom the author sees As Cassatt's most inspiring muse. Chessman hauntingly brings to life Paris in 1880, with its thriving art world.