The real weakness of the concordat is that in that age of per sonal influence little value was attached to any document. A written decision would not necessarily be effective. Consequently the concordat was no secure guarantee for the future. Moreover though the empire claimed universal rule, its effective power was at best over Germany and Italy. Elsewhere in Europe therefore the concordat had no value at all, save as a precedent for similar difficulties.
Thus after defeating the State in its open effort to control the souls of men the Church led by the papacy had prevented the State from direct intervention in religious matters; later tem poral rulers had been able to usurp a practical disciplinary con trol over ecclesiastical authorities. At length the papacy had asserted itself, used its universal authority, manifested the unity of the Church and vindicated its supreme power over the souls of men. Christendom is one society, and in that society the spiritual authority is paramount because of its greater dignity, and the far greater importance of its work. In any difficulties between spir itual and temporal rulers the spiritual must be the judges, for without treason to Christ they may not permit anything earthly however important to interfere with the work of salvation. If therefore the rulers of the Church—even mistakenly—judge that this work is hampered by some temporal policy, loyal Christians must abide by the decision. Before this these truths had been believed and taught, but they had never been given so clear a practical expression as during the investiture struggle.
After the concordat there was a short interlude. The papacy consolidated its position under the influence of St. Bernard. Fred eric Barbarossa however on coming to the Imperial throne began a reaction. In his desire to re-establish fully the Imperial author ity he wished to abolish the recently asserted clerical independence. Moreover papal temporal power had been extended. Various feudal claims had been made, and some were recognized. The Countess Matilda of Tuscany had left her great possessions to the papacy, and it was at least tenable that the bequest was lawful. On these bases there had been growing at Rome a tendency hardly expressed, to claim feudal authority over all princes, even over the emperor. This papal tendency, and the actual papal temporal power, was obviously even more opposed to Barbarossa's ambi tions than clerical independence. Consequently there is- in the ensuing struggle much justice on the Imperial side. But Fred eric's appointment of an anti-Pope and his excessive claims justi fied the vigour of Alexander III.'s resistance to him. In 1177 the Peace of Venice settled the dispute roughly in favour of the Church. The independence of the papacy in its rule of the Church had again been vindicated, and the claims to feudal authority though left in abeyance had not been finally abandoned.
The early death of Frederic's son Henry VI. saved the papacy from a severe struggle, and the election of Innocent III. brought the papacy to its maximum power. Innocent, a man of high ideals and of great ability, was the guardian of Frederic II., Henry's youthful son. The pope secured for his ward his Sicilian inheritance. But he definitely excluded him for some time from the empire, which he rightly declared was not hereditary. He further declared that the papacy was even temporarily the supe rior power : the popes had founded the empire in the West ; they made a king emperor by crowning him ; therefore they had the responsibility of seeing that the emperor designate was worthy, before they could conscientiously give to him the authority that was in their keeping. Innocent therefore claimed a right of veto, which was almost equivalent to the right to appoint. This claim fortune and his own ability enabled him to make good. The situ ation of Henry III.'s days was almost exactly reversed. Else where also Innocent claimed a right of supervision over princes even in temporal affairs. This, though it goes beyond St. Gregory's explicit claims, is consistent with them, and even their logical sequel. Any temporal action may affect the spiritual destinies of men and may therefore come within the province of the supreme spiritual authority.
On Innocent's death new troubles arose. Frederick II. no longer a minor showed himself able, ambitious, and unscrupulous. The main source of dispute was his revival of Barbarossa's schemes despite his oaths against such revival. But as the conflict pro gressed, he apparently claimed even supreme spiritual authority; he certainly arrogated some spiritual supremacy. Gregory IX. the first pope to oppose him was succeeded by Innocent IV. Innocent's methods were deplorable, and the bitterness of the struggle alienated sympathy from both parties. Ultimately Fred eric's death enabled the papacy to secure a Pyrrhic victory. The subsequent extinction of the Hohenstaufen family (that of Bar barossa), though the papacy was probably not responsible for the crime, made the empire no longer a serious rival to the papacy for universal rule. However, the long bitter struggle, its ferocity, its intrigues, the financial exactions necessary for its maintenance had cost the papacy much of its prestige. The Italian successes of Charles of Anjou, the rising power of French nationalism, and the growing French influence at Rome itself indicated where the next difficulty was to be. When there was under the empire some shadow of universal temporal authority, Innocent III.'s solution of the problem of the relations between Church and State might have been made practicable. But the formation of nations made a new solution necessary.