Although two separate women in being and entity, these two women were so important together and couldn't be separated. So, these women count as one unit. I'm sure they would have liked it this way.
Sarah was born on November 26, 1792, and Angelina was born on February 20, 1806. Around 1821, Sarah went to visit Philadelphia and met the Society of Friends, which she became a member of in 1821, staying in Philadelphia. Angelina, following her sister's lead, became a member of the Society of Friends in Philadelphia in 1829, though she also became a Quaker. The beginning of their great importance was started by Angelina, however. Angelina wrote a letter to William Lloyd Garrison on how slavery should be abolished, and it was published in his newspaper, The Liberator. So, Angelina continued writing.
In 1836, Angelina wrote An Appeal to the Christian Women of the South, a pamphlet that addressed the moral view against slavery. This time, Sarah followed her lead and wrote An Epistle to the Clergy of the Southern States. Both joined the AntiSlavery Society and began preaching privately on how it should be abolished. Then, someone came up to them and reminded them that women deserve rights too. So, they started preaching on women's rights, too.
In 1837, Angelina wrote An Appeal to the Women of the Nominally Free States, and in 1838, Sarah wrote Letters on the Equality of the Sexes and the Condition of Woman. Also in 1838, Angelina married Theodore Dwight Weld, an abolitionist like Sarah and Angelina. Sarah, Angelina, and Weld together wroteSlavery As It Is: Testimony of a Thousand Witnesses.
This book marked the end of Sarah and Angelina's preaching for slavery's abolition and women's rights. Sarah and Angelina spent the rest of their years working at Weld's school and moving to West Newton, Massachusetts, and Boston. Sarah died on December 23, 1873, and Angelina died on October 26, 1879.