Genera of being.

Above is a graphic (courtesy of Nature Master Encyclopedia) that illustrates the current Chain or Genera of Being as we now consider it. This effort to relate beings one to another, viz. Kingdom, Phylum, Class, Order, Family, Genus, and Species (”Life” and “Domain” are recent additions), was originally instituted by Linnaeus through the work of Aristotle, and was the first significant step to doing real practical science. Indeed, it was practical science.