Calvin C. Foster (1829-?) was born in Hampton, Connecticut, and most likely died in Connecticut. He was a student of Mary Baker Eddy's, taking Primary class (1885) alongside his wife, Sarah, and later taking Normal class (1886). For over thirty years, the Fosters owned and taught at an "English, Classical and Commercial" school at 476 Main Street in Worcester, Massachusetts. After studying with Eddy, the Fosters incorporated a Metaphysical healing and teaching practice into the curriculum at their school. There is no record of them joining the Christian Scientist Association or uniting with the Church of Christ (Scientist).

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