points attackable, and do what he can; deflect currents in the right direction; above all, sow ideals, and wait upon the ministrations of time.  He must take conditions as he finds them, following the lines of least resistance.  It is nothing to him that posterity may ask, Why did he not change this or that?—­and add he was no better than he should be.  At once to change outer things and ways of feeling that have grown up through centuries is not difficult but impossible; and sometimes right courses, violently taken, are wronger than wrong ones.  Augustus was a man of peace, if anybody ever was, yet (as in Spain) made many wars.  The result of this Spanish conquest was that the Pax Romana came into Spain, bringing with it severa centuries of high prosperity; the world-currents flowed in there at once and presently the light of Spain, such as it was at that time, shone out over the Roman world.  Most of the great names of the first century A.D. are those of Spaniards.

After Spain, the most immediate frontier difficulty was with Parthia; and there Augustus won his greatest victory.  At Carrhae the Parthians had routed Crassus and taken the Roman eagles.  Rome was responsible for the provinces of Asia; and she was nominally at war with Parthia,—­so those provinces were in trim to be overrun at any time.  The war, then, must be finished; and could Rome let it end on terms of a Parthian victory?  Where (it would be argued) would then be Roman prestige?  Where Roman authority (a more real and valuable thing)?  Where the Pax Romana?—­All very true and sound; everybody knew that for the war to reopen was only a question of time;—­Julius had been on the point of marching east when the liberators killed him.  Yes, said Augustus; the matter must be attended to.  But Parthia was a more of less civilized power:  a state at least with an established central government; and when you have that, there is generally the chance to settle things by tact instead of by fighting.  He found a means.  He opened negotiations, and brought all his tact to bear.  He was the chief, and a bridge again.  Over which presently came Phraates king of Parthia, amenable and well-disposed, to return the eagles and such of the prisoners as were still alive.  Rome had won back her prestige; Parthia was undegraded; peace had won a victory that war would have spent itself in vain striving after.

But the frontier was enormous, and nowhere else marched with that of an established power.  There was no winning by peace along that vast northern line from the Black to the North Sea, at the most vital spot of which an unlucky physical geography makes Italy easily invadable and rather hard to defend.  Negotiations would not work here, since there was no union to negotiate with; only ebullient German tribes whose game was raiding and whose trade plunder.  So the Alps had to be held, and a line drawn somewhere north of them,—­say along the Danube and the Rhine or Elbe; a frontier that could be made safe