David S. Reynolds, John Brown, Abolitionist: The Man Who Killed Slavery, Sparked the Civil War, and Seeded Civil Rights, rev. ed. (New York: Vintage Books, 2005), 49-50.
Unlike the erratic Dianthe [Lusk Brown], Mary would prove to be a rock of stability for John Brown. Staunch and stoical, she set a tone of quiet courage that would influence the whole family. At the time of her marriage she was only half Brown's age and four years older than his oldest son, but her stepchildren would always call her "Mother." She would endure the deaths of nine of the thirteen children she had with John Brown, including four in one terrible week in 1842. Only four of her children outlived her. She stood behind her husband in times of poverty, long separation, and mortal danger. During his trial friends suggested that she try to save him by testifying that he was insane. She replied flatly, "It would be untrue, and therefore impossible."