But unless circumstances are constant, it matters little how constant tempers and tendencies may be; and the expectations which we found upon the general action of avarice, credulity, bigotry, self-seeking, or any of the debased forms of legitimate human impulses, will often be disappointed by results.  Prepare the favorite climate, moisture, exposure of a foreign plant, imitate its latitude and air and soil:  it will not necessarily grow at all, or, growing, it will only surprise you by some alteration of its native features.  Results are better chemists than we, and their delicate root-fibres test the ground more accurately; we shall find them languishing for some favorite elements, or colored and persuaded by novel ones.  History must remember the constants of Man and of Nature, but be always expecting their variables, lest her prophetic gift fall into ill-repute.

Thus, give unlimited power to the Catholic, and he cannot anywhere set up his old-fashioned absolutism, unless you can manage at the same time to furnish him with Roman and Spanish people, and the fifteenth century.  Yet we, too, have trembled at the imaginary horrors of Popery.  All the power you can thrust and pile upon the Catholic in America will become an instrument to further the country’s tendency towards light, as it drags the human impulses away from the despotic past.  All the Jesuits, and prize bulls by every steamer, relays of papal agents, and Corpus-Christi processions in the streets of Boston, will hardly lift the shoulders of the great protesting country, as it turns to stare from its tilling, steaming, pioneering, emancipating task.

It is not difficult to see why the revolts of peasants in the Middle Ages were marked by horrible excesses,—­why diplomatic Catholicism prepared a St. Bartholomew’s Eve for Paris,—­why Dutch and Scotch Protestants defaced and trampled under foot ecclesiastical Art,—­why German princes proclaimed a crusade against budding Protestantism and Pan-slavism under Ziska and Procopius in Bohemia,—­why the fagots were fired at Constance, Prague, and Smithfield, and Pequod wigwams in New England.  All dreadful scenes, by simply taking place, show that they have reason for it.  But will they take place again?  A Black Douglas did undoubtedly live, and he was the nursery-threat for fractious Scotch children during several generations; the Douglas never caught one of them, but the threat did.  So we are plied with stock-phrases, such as “the Reign of Terror” and “the Horrors of San Domingo,” and History is abjectly conjured not to repeat herself, as she certainly will do, if she goes on in the old way.  Of course she will.  But does she propose to furnish a fac-simile of any critical epoch which haunts the imaginations of mankind?  That depends upon circumstances.  The same barrel will play a fresh tune by a hair’s-breadth shifting of a spring.  Two epochs may seem to be exactly alike, and the men who only remember may seek to terrify the men who hope by exposing the resemblance.  But unless they can show that all the circumstances are identical, they have no right to infect the morning with their twilight fears.  History insensibly modifies her plan to secure the maximum of progress with the minimum of catastrophes, and she repels the flippant insinuation that her children win all their fresh advantages at the expense of the old crimes.