J. B. BURY, 1932: The Idea of Progress --An Inquiry into its Origin and Growth, Macmillan Publishing Co. Inc.; reprint 1982, Westport Conn.: Greenwood Press.

... The term "world," orbis (terrarum), which imperial poets are usually freely in speaking of the Empire, is more than a mere poetical or patriotic exaggeration; it expresses the ideas, the unrealised ideal of the Empire. ... There we have the notion of the human race apprehended as a whole, the ecumenical idea, imposing upon Rome the more humanely by Pliny as the creation of a single fatherland for all the peoples of the world. ...

The idea, which in the Roman Empire and in the Middle Ages took the form of a universal State and a universal Church, passed afterwards into the conception of the intercohesion of peoples as contributors to a common pool of civilization -- a principle which, when the idea of Progress at last made its appearance in the world, was to be one of the elements in its growth. [p. 24]