We had an introduction to the bold ideas of naturalist Carolus Linnaeus in the previous chapter (Figure 4.1). You will remember that he wanted first to identify unambiguously every living thing on the planet and second to organize the living world into as simple a system as possible. He coined the term taxonomy as a slightly irregular mash-up of the Greek words taxis, meaning arrangement, and nomos, meaning method. Thus, the modern science of describing and classifying living things began with Linnaeus and – with fewer modifications than you might guess – his system is still used today. No wonder. The structure he conceived was positively brilliant. His revolutionary innovation was the invention of a rule-based, hierarchical system that unequivocally differentiated species from one another, gave every organism a unique name, and specified the relationships among species.