
Botanists and zoologists in the 18th Century faced an explosion of species. What they needed was the equivalent of a search engine, and Carl Linnaeus rose to the challenge. He invented a cataloguing system that made it possible to find out whether a specimen belonged to a known species, and if it did, where more information could be found. His system was more powerful than an index, which requires knowing a name to begin with, while a user of his system could begin with an unnamed specimen. Linnaeus insisted that every group in his new ranks, order and class, must have a one-word name, which was a deliberate and powerful innovation. In his Systema Naturae those names were printed as running heads. This layout enabled a user to start with the higher categories and navigate downwards. Although he is often celebrated for his two-word format for the names of species, his attention to the names of groups above the rank of genus is often overlooked.