Categories are human impositions upon nature (though nature's factuality offers hints and suggestions in return). Consider, as an example, the 'obvious' division of humans into two sexes. We may view male versus female as a permanent dichotomy, as expressions of two alternative pathways in embryological development and later growth. How else could we possibly classify people? Yet this 'two-sex model' has only recently prevailed in Western history, and could not hold sway until the mechanical philosophy of Newton and Descartes vanquished the Neoplatonism of previous worldviews. From classical times to the Renaissance, a 'one-sex model' was favored, with human bodies ranged on a continuum of excellence, from low earthiness to high idealization. To be sure, people might clump into two major groups, called male and female, along this line, but only one ideal or archetypal body existed, and all actual expressions (real persons) had to occupy a station along a single continuum of metaphysical advance. This older system is surely as sexist as the later 'two-sex model' (which posits innate and predetermined differences of worth from the start), but for different reasons -- and we need to understand the depth of oppression through the ages.