In Plato's Phaedrus, Socrates famously described the virtues of two ways of looking at the world. The first entailed "seeing together things that are scattered about everywhere and collecting them into one kind," while the second was the skill "to cut up each kind according to its species along its natural joints, and to try not to splinter any part, as a bad butcher might do." In a similar sentiment, Darwin wrote in 1857, "It is good to have hair-splitters and lumpers." How have scientists and laypeople perceived similarities and differences in the living world? How have they divided nature into distinct kinds and individuals? How have they distinguished between parts and wholes? Where have they positioned human beings within nature's order? What were the consequences of finding different kinds of order in nature? This course explores these and related questions historically. We will consider different approaches to making sense of nature, and how a multitude of perspectives have been brought to bear on this ordering project. Topics covered include taxonomy and classification, race science and scientific racism, gender and sex differences, disease categories and immune selfhood, and symbioses and biogeochemical cycles.