So, to instruct his students and the people as to the true ground of justification, which he had worked out from the study of the Bible and Saint Augustine amid the agonies of a tormented conscience, Luther prepared his theses,--those celebrated ninety-five propositions, which he affixed to the gates of the church of Wittenberg, and which excited a great sensation throughout Northern Germany, reaching even the eyes of the Pope himself, who did not comprehend their tendency, but was struck with their power. "This Doctor Luther," said he, "is a man of fine genius." The students of the university, and the people generally, were kindled as if by Pentecostal fires. The new invention of printing scattered those theses everywhere, far and near; they reached the humble hamlet as well as the palaces of bishops and princes. They excited immediate and immense enthusiasm: there was freshness in them, originality, and great ideas. We cannot wonder at the enthusiasm which those religious ideas excited nearly four hundred years ago when we reflect that they were not cant words then, not worn-out platitudes, not dead dogmas, but full of life and exciting interest,--even as were the watchwords of Rousseau--"Liberty, Fraternity, Equality"--to Frenchmen, on the outbreak of their political revolution. And as those watchwords--abstractly true--roused the dormant energies of the French to a terrible conflict against feudalism and royalty, so those theses of Luther kindled Germany into a living flame. And why? Because they presented more cheerful and comforting grounds of justification than had been preached for one thousand years,--faith rather than penance; for works hinged on penance. The underlying principle of those propositions was _grace_,--divine grace to save the world,--the principle of Paul and Saint Augustine; therefore not new, but forgotten; a mighty comfort to miserable people, mocked and cheated and robbed by a venal and a gluttonous clergy. Even Taine admits that this doctrine of grace is the foundation stone of Protestantism as it spread over Europe in the sixteenth century. In those places where Protestantism is dead,--where rationalism or Pelagian speculations have taken its place,--this fact may be denied; but the history of Northern Europe blazes with it,--a fact which no historian of any honesty can deny.