In the last few years, for purposes that need not now concern us, I have had to study a certain amount of history and a number of historians. Many men of commanding intelligence have been historians, and I offer no comparison between the intellectual quality of historians and that of scientific men as such. But trained as I was in the clear, subtle and beautiful disciplines of comparative anatomy, I found myself amazed at the easy carelessness of the average historian’s habitual terminology, his slovenly parallelisms and reckless assumptions. A large part of his work is the study of human communities and political associations. Yet I found him without any intelligible classification of political combinations, any real sense of grades and structural differences between one community and another. He slops the word “Empire” over the whole face of history; Athenian Empire and Aztec Empire, Shang Empire and Sung Empire, Empire of Alexander and Roman Empire, Mongol Empire and Hittite Empire, British Empire and Brazilian Empire; it’s all the same to him. “Cats is dogs,” as the porter said, “rabbits is poultry, but a parrot is a passenger.” As a consequence, the historian argues from the most atrocious analogies. And, though there is a considerable and pretentious literature of political science, there does not yet exist in all political and historical literature any attempt at a clear analysis of the differences and affinities of all these various human complexes. Yet to make such an analysis would be a most attractive and fruitful task. Historical and political science has still to find its Linnæus. History, until that happens, remains a slough of terminological confusion, and the ideas of the ordinary educated man drown in that mud.