Based on a wide range of Latin and vernacular sources, this essay reexamines Thomas Laqueur's and Londa Schiebinger's influential claim that the idea of incommensurable anatomical difference between the sexes was "invented" in the eighteenth century, reflecting, in particular, a need to resort to nature in order to justify female subordination against new ideals of equality and universal rights. It provides ample evidence that already around 1600 many leading physicians, rather than proclaiming a "one-sex model" of female inferiority, insisted on the unique and purposeful features of the female skeleton and the female genital organs and illustrated them visually. The author shares Laqueur's and Schiebinger's assumption that the shift toward incommensurable anatomical difference helped legitimize woman's subordinate position as housewife and mother as naturally given. But around 1600 Enlightenment ideals as yet played no role. Instead, this shift reflected, in particular, contemporary physicians' growing appreciation of personal discovery and innovation, the rise of a specialist gynecology, and new views on marriage and motherhood in the upper classes among whom the physicians lived and whose support they sought.