Throughout her life, in her personal relationships as well as in her role as a public intellectual, the English thinker Mary Astell (1666-1731) supported women, wrote to and for women, and, to the greatest extent possible, moved from advocacy to action on their behalf. In Some Reflections upon Marriage (London, 1700), Astell focused her attention on the institution of marriage. For Astell, marriage is a divinely ordained state, a "Christian institution,"...