Here is a mighty river:  the practical uses of mankind are mainly concerned with it as far up as it may be navigable; or at most, as far up as it may be turning mills and watering the fields of agriculture.  There may be regions beyond when poets and mythologists may bring great treasures for the Human Spirit; but do you do well to treat such treasures as plug material for exchange and barter?  They call for another kind of treatment.  The sober science of history may be said to start where the nations become navigable, and begin to affect the world.  You can sail your ships up the river Rome to about the beginning of the third century B.C., when she began to ermerge from Italian provincialism and to have relations with foreign peoples:  Pyrrhus came over to fight her in 280.  What is told of the century before may be true or not; as a general picture it is probably true enough, and only as a general picture does it matter; its details are supremely unimportant.  The river here is pouting through the gorges, or shallowly meandering the meads.  It is watering Farmer Balbus’s fields; Grazier Ahenobarbus’s cows drink at it; idle Dolabell angles in its quiet reaches:  there are bloody tribal affrays yearly at its fords.  It is important, certainly, to Babbus and Dolabella, and the men slain in the forays;—­but to us others—.

And then at 390 there are falls and dangerous rapids; you will get no ships beyond these.  The Gauls poured down and swept away everything:  the records were burnt; and Rome, such as it was, had to be re-founded.  Here is a main break with the past; something like Ts’in Shi Hwangti’s Book-burning; and it serves to make doubly uncertain all that went before.  Go further now, and you must take to the wild unmapped hills.  There are no fields beyond this; the kine keep to the lush lowland meadows; rod and line must be left behind,—­and angler too, unles he is prepared for stiff climbing, and no marketable recompense.  Nor yet, perhaps, for some time, much in things unmarketable:  I will not say there is any great beauty of scenery in these rather stubborn and arid hills.

As to the fourth century, then (or from 280 to 390)—­we need not care much which of Ahenobarbus’s cows was brindled, or which had the crumpled horn, or which broke off the coltsfoot bloom with lazy ruthless hoof.  As to the fifth,—­we need not try to row the quinqueremes of history beyond that Gaulish waterfall.  We need not bother with the weight Dolabella claims for the trout he says he caught up there:  that trout has been cooked and eaten these twenty-three hundred years.  Away beyond, in the high mountains, there may be pools haunted by the nymphs; you cannot sail up to them, that is certain; but there may be ways round.....