The view of human manners, in all their variety of appearances, is both profitable and agreeable; and if the aspect in some periods seem horrid and deformed, we may thence learn to cherish with the greater anxiety that science and civility, which has so close a connection with virtue and humanity, and which, as it is a sovereign antidote against superstition, is also the most effectual remedy against vice and disorders of every kind.
The rise, progress, perfection, and decline of art and science, are curious objects of contemplation, and intimately connected with a narration of civil transactions.

The events of no particular period can be fully accounted for, but by considering the degrees of advancement which men have reached in those particulars.
Those who cast their eye on the general revolutions of society, will find that, as almost all improvements of the human mind had reached nearly to their state of perfection about the age of Augustus, there was a sensible decline from that point or period; and men thenceforth relapsed gradually into ignorance and barbarism.

The unlimited extent of the Roman empire, and the consequent despotism of its monarchs, extinguished all emulation, debased the generous spirits of men, and depressed that noble flame by which all the refined arts must be cherished and enlivened.

The military government, which soon succeeded, rendered even the lives and properties of men insecure and precarious; and proved destructive to those vulgar and more necessary arts of agriculture, manufactures, and commerce; and, in the end, to the military art and genius itself, by which alone the immense fabric of the empire could be supported.

The irruption of the barbarous nations which soon followed, overwhelmed all human knowledge, which was already far in its decline; and men sunk every age deeper into ignorance, stupidity, and superstition; till the light of ancient science and history had very nearly suffered a total extinction in all the European nations.
But there is a point of depression, as well as of exaltation, from which human affairs naturally return in a contrary direction, and beyond which they seldom pass either in their advancement or decline.