Today I first learned about proto-feminist Mary Wollstonecraft. I can barely fathom how any person could muster the courage to take such a strong moral stand in 1792. You don’t need much imagination to understand the abuse she took as a result of writing her book. History is filled with many such “insane” ideas that eventually become common sense.
From Wikipedia:

A Vindication of the Rights of Woman: with Strictures on Political and Moral Subjects (1792), written by the 18th-century British proto-feminist Mary Wollstonecraft, is one of the earliest works of feminist philosophy. In it, Wollstonecraft responds to those educational and political theorists of the 18th century who believed that women should not receive a rational education. . . . Wollstonecraft maintains that women are human beings deserving of the same fundamental rights as men, and that treating them as mere ornaments or property for men undermines the moral foundations of society. . . . She launched a broad attack against sexual double standards, indicting men for encouraging women to indulge in excessive emotion. Wollstonecraft hurried to complete the work in direct response to ongoing events; she intended to write a more thoughtful second volume but died before completing it.