In this mental torture he wandered throughout Italy, from town to town, and from the palace of one of his benefactors to that of another, without ever finding a resting place for his wounded spirit. He stooped in vain to address letters of supplication to the Florentines; the rancour of his enemies was not to be softened by prayers. Meanwhile the hopes of the Ghibelines were again raised, when Henry VII., who had been elected Emperor in 1308, entered Italy to regain the rights of sovereignty which his predecessors had lost. Elated by the better prospects which appeared to open, Dante became a strenuous advocate of the imperial cause. He composed a treatise on monarchy, in which he asserted the rights of the empire against the encroachments of the Court of Rome: he wrote a circular both to the Kings and Princes of Italy, and to the Senators of Rome, admonishing them to give an honourable reception to their Sovereign; and he sent a hortatory epistle to the Emperor himself, urging him to turn his arms against Florence, and to visit that refractory city with severe punishment. Henry did accordingly lay siege to Florence in September, 1312, but without success; and the hopes of the Ghibelines were finally extinguished in the following August, by his death, under strong suspicion of poison. Thus Dante, in consequence of his recent conduct, saw himself farther than ever from restoration to his beloved Florence. The unfortunate exile, now reduced to despair, resumed his wanderings, often returning to Verona, where the Scaligeri family always received him at their court with peculiar kindness. It has been asserted that his thirst for knowledge led him to Paris and Oxford. His journey to England is still involved in doubt; but it appears certain, that he visited Paris, where he is said to have acquired great fame, by holding public disputations on several questions of theology.