 Valentine was born in Spencer, New York on May 9, 1862, the son of William Valentine, a farmer and horse breeder and Electa Brown Valentine.After taking the normal course at Mansfield Normal School in Pennsylvania, he taught school for four years and then enrolled at the Colgate Theological Seminary.After completing his studies, he joined the American Baptist Foreign Mission Society and was sent to Burma – first in 1895 to Rangoon, then to Mandalay where he became principal of the Baptist Mission High School for Boys.