Across from the shelf where the cookbooks sit in Heloísa Gelber Rivas's Boston kitchen, are a set of the real "cook" books— Science and Health by Mary Baker Eddy, the Bible, concordances, and a Christian Science Hymnal. In fact, they're in every room of her condominium, an old habit from when Heloísa's late husband, Horacio, was First Reader at The Mother Church, and the couple lived in the First Reader's residence on Commonweath Avenue.