If we subdivide a large class into smaller classes, and, again, subdivide these subdivisions, we come at last to single objects.
Men
|
—————————
Europeans, Asiatics, etc.
|
——————————
Englishmen, Frenchmen, etc.
|
——————————
John Doe, Richard Roe, etc.
A table of higher and lower classes arranged in order has been known from of old as a tree of division or classification. The following is Porphyry's "tree":—