Sarah D. Frothingham (1814-1903) was an active member of the early Christian Scientist Association and Church of Christ (Scientist). She was a student of Mary Baker Eddy's, studying with her in June 1876. She attended early meetings of the Christian Scientist Association in Lynn, Massachusetts, and in the late 1870s, some meetings of the Association were held at Frothingham's home at 124 West Newton Street in Boston, Massachusetts. At an early Thanksgiving service in about 1878, Frothingham is credited with giving an emotive testimony that moved Mary Baker Eddy to remark, "such an expression helped the cause more than she [Frothingham] could know." She submitted her resignation from the Association on December 25, 1881, after earlier writing to tell Eddy that she was resigning.

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