The dissolution of the empire of Karl the Great began in the reign of his son and successor, Ludwig, with the disintegration of the public service and the attacks of Northmen and Slavs on the frontier. The invasions of the Northmen are mentioned by Einhard as occurring in the last days of Karl (no. 7, chapter 14). In the reigns of Ludwig and his successors the invaders continually ravaged the shores of Gaul and northern Germany and added materially to the distress of the period. This letter refers in its last part to one of these raids, but it is interesting chiefly as an illustration of the mental attitude of the men of its age. It is believed by almost all the ancient authorities that the appearance of new and unknown heavenly bodies portends to wretched mortals direful and disastrous events, rather than pleasant and propitious ones. The sacred scriptures alone tell of the propitious appearance of a new star; that is, that star which the wise men of the Chaldæans are said to have seen when, conjecturing from its most brilliant light the recent birth of the eternal king, they brought with veneration gifts worthy the acceptance of so great a lord. But the appearance of this star which has lately arisen is reported by all who have seen it to be terrible and malignant. And indeed I believe it presages evils which we have deserved, and foretells a coming destruction of which we are worthy. For what difference does it make whether this coming danger is foretold to the human race by man or angel or star? The important thing is to understand that this appearance of a new body in the heavens is not without significance, but that it is meant to forewarn mortals that they may avert the future evil by repentance and prayers. Thus by the preaching of the prophet Jonah the destruction of the city, which had been threatened by him, was deferred because the inhabitants turned from their iniquities and evil lives.... So we trust that merciful God will turn this threatened evil from us also, if we like them repent with our whole hearts. Would that the destruction which the fleet of the Northmen is said to have inflicted upon this realm recently might be regarded as the sufficient occasion for the appearance of this comet, but I fear that it is rather some new distress still to come that is foretold by this terrible omen. 16. The Strassburg Oaths, 842. Nithard, III, 5; M. G. SS. folio, II. pp. 665 ff.