The Editors desire to thank the members of the Acton family for their help and advice during the preparation of this volume and of the volume of Historical Essays and Studies. They have had the advantage of access to many of Acton's letters, especially those to Dollinger and Lady Blennerhasset. They have thus been provided with valuable material for the Introduction. At the same time they wish to take the entire responsibility for the opinions expressed therein. They are again indebted to Professor Henry Jackson for valuable suggestions. This volume consists of articles reprinted from the following journals: The Quarterly Review, The English Historical Review, The Nineteenth Century, The Rambler, The Home and Foreign Review, The North British Review, The Bridgnorth Journal. The Editors have to thank Mr. John Murray, Messrs. Longmans, Kegan Paul, Williams and Norgate, and the proprietors of The Bridgnorth Journal for their kind permission to republish these articles, and also the Delegacy of the Clarendon Press for allowing the reprint of the Introduction to Mr. Burd's edition of Il Principe. They desire to point out that in Lord Acton and his Circle the article on "The Protestant Theory of Persecution" is attributed to Simpson: this is an error. J.N.F. R.V.L. August 24, 1907