One of the first of them is my friend, Mr. Edward Everett, who, in his long and brilliant career as a statesman, has lost nothing of that love of letters which formed his first claim to distinction. The year before his appointment to the English mission he passed on the Continent, where, with the kindness that belongs to his nature, he spent much time in examining for me the great libraries, first in Paris, and afterwards more effectually in Florence. From the _Archivio Mediceo_, in which he was permitted by the grand duke to conduct his researches, he obtained copies of sundry valuable documents, and among them the letters of the Tuscan ministers, which have helped to guide me in some of the most intricate parts of my narrative. A still larger amount of materials he derived from the private library of Count Guicciardini, the descendant of the illustrious historian of that name. I am happy to express my lively sense of the courtesy shown by this nobleman; also my gratitude for kind offices rendered me by Prince Corsini; and no less by the Marquis Gino Capponi, whose name will be always held in honor for the enlightened patronage which he has extended to learning, while suffering, himself, under the severest privation that can befall the scholar. There was still an important deficiency in my collection,--that of the _Relazioni Venete_, as the reports are called which were made by ambassadors of Venice on their return from their foreign missions. The value of these reports, for the information they give of the countries visited by the envoys, is well known to historians. The deficiency was amply supplied by the unwearied kindness of my friend, Mr. Fay, who now so ably fills the post of minister from the United States to Switzerland. When connected with the American legation at Berlin, he, in the most obliging manner, assisted me in making arrangements for obtaining the documents I desired, which, with other papers of importance, were copied for me from the manuscripts in the Royal Library of Berlin, and the Ducal Library of Gotha. I have also, in connection with this, to express my obligations to the distinguished librarian of the former institution, Mr. Pertz, for the good-will which he showed in promoting my views. Through Mr. Fay, I also obtained the authority of Prince Metternich to inspect the Archives of the Empire in Vienna, which I inferred, from the intimate relations subsisting between the courts of Madrid and Vienna in that day, must contain much valuable matter relevant to my subject. The result did not correspond to my expectations. I am happy, however, to have the opportunity of publicly offering my acknowledgments to that eminent scholar, Dr. Ferdinand Wolf, for the obliging manner in which he conducted the investigation for me, as well in the archives above mentioned, as, with better results, in the Imperial Library, with which he is officially connected.