Mary V. Blain (b. Vandewater) (1848-1907) was born in Sidney Township, Ontario, Canada, and died in Chicago, Illinois. She immigrated to the United States in 1865 and married Julian Blain, a merchant and later a building contractor, in Kankakee, Illinois, in 1869. The Blains moved to Chicago in the early 1880s. After Mary experienced a healing through Christian Science treatment by Lucinda Willsie, both Blains became interested in Christian Science and studied with Mary Baker Eddy. Mary Blain completed the Primary course in August 1886, the Obstetrics course in October 1888, and the Normal course in May 1889, and Julian completed the Normal course in November 1898. The Blains were instrumental in establishing First Church of Christ, Scientist, Chicago. They both served on its Board of Directors and Julian served on its building committee. Mary and Julian both joined The First Church of Christ, Scientist, in Boston, Massachusetts, on September 30, 1893, and both were listed in The Christian Science Journal from 1894 until their respective passings, Mary as a practitioner and teacher and Julian as a practitioner. Mary Blain was called to serve in Eddy's Pleasant View household from 1905 to 1906.

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