That history repeats itself has become a kind of truism, but of as little practical value in helping us to form our opinions as other similar labor-saving expedients to escape thought. Sceptical minds see in human affairs a regular oscillation, hopeful ones a continual progress, and both can support their creeds with abundance of pertinent example. Both seem to admit a law of recurrence, but the former make it act in a circle, the latter in a spiral. There is, no doubt, one constant element in the reckoning, namely, human nature, and perhaps another in human nature itself,--the tendency to reaction from all extremes; but the way in which these shall operate, and the force they shall exert, are dependent on a multitude of new and impredicable circumstances. Coincidences there certainly are, but our records are hardly yet long enough to furnish the basis for secure induction. Such parallelisms are merely curious, and entertain the fancy rather than supply precedent for the judgment. When Tacitus tells us that gladiators have not so much stomach for fighting as soldiers, we remember our own roughs and shoulder-hitters at the beginning of the war, and are inclined to think that Macer and Billy Wilson illustrated a general truth. But, unfortunately, Octavius found prize-fighters of another metal, not to speak of Spartacus. Perhaps the objections to our making use of colored soldiers (_hic niger est, hunc tu, Romane, caveto_) will seem as absurd one of these days as the outcry that Caesar was degrading the service by enlisting Gauls; but we will not hazard a prophecy. In the alarm of the Pannonian revolt, his nephew recruited the army of Italy by a conscription of slaves, who thereby became free, and this measure seems to have been acquiesced in by the unwarlike citizens, who preferred that the experiment of death should be made _in corpore vili_ rather than in their own persons.