Once the second half of the 19th century arrived, there was beginning to be a rise in opposition to marriage involving minors. Elizabeth Oakes Smith, a women's rights activist, was married on March 6, 1823 at age 16 to man named Seba Smith, a man who was age 30 when they married. Elizabeth later went against marriage of young girls because she thought when she was married, she was "a mere baby, no more fit to be a wife than a child of ten years." By the 1850s, Elizabeth had become a vocal participant in the nascent women's rights movement. Inspired by her experience as a married 16 year old and becoming a mother soon thereafter, one of Elizabeth's main targets was the early marriage of girls. She became the movement's spokeswoman against early marriage of girls. Elizabeth believed that many of the problems in marriage, including divorce, were caused by early marriages, where girls didn't know their minds enough to understand the choices they made, which Elizabeth called the "great life-long mistake". What mattered more for Elizabeth is she believed that early marriage deprived girls of girlhood itself, the stage of life where girls can be educated, have fun, and preserve their innocence before the labor of wife- and motherhood begin. The 1850s was when opposition to early marriage was beginning to rise. The Reverend Antoinette Brown Blackwell spoke at tenth National Women's Rights Convention in 1860. She said "Let her be taught that she ought not to be married in her teens. Let her wait, as young man does, if he is sensible, until she is 25 or 30." In The Moral Philosophy of Courtship and Marriage (1857), William Alcott, one of the most widely read doctors of the mid-19th century, advocated that women and men not marry until they were physically mature, which in the man was 25 or 26 years old and the woman was 21 or 22 years old.