jean h. baker, historian and biographer of mary todd lincoln, describes the relationship between lincoln and his wife as "bound together by three strong bonds—sex, parenting and politics". in addition to the anti–mary todd bias of many historians, engendered by william herndon's (lincoln's law partner and early biographer) personal hatred of mrs. lincoln, baker discounts historic criticism of the marriage. she says that contemporary historians have a basic misunderstanding of the changing nature of marriage and courtship in the mid-19th century, and attempt to judge the lincoln marriage by modern standards.