Mr. Oliver P. Barrett of Chicago has given me great joy in the examination of his fine collection of Lincoln manuscripts. I have spent a few pleasant and profitable hours in the collection of Honorable Daniel Fish, the noted Lincoln bibliographer, of Minneapolis, and thank him for his friendly interest in this undertaking. Among libraries, my largest debt is to those of the Chicago Historical Society, the Illinois State Historical Society at Springfield, and the Library of Congress in Washington. In each of these I have had not only unrestricted access to the whole Lincoln material possessed by them, but the most generous and courteous assistance. I have examined every rare Lincoln book, and many manuscripts, in these three collections. I have had occasion also to use the Chicago Public Library, the Newberry Library, and the Library of the University of Chicago, as well as those of Chicago Theological Seminary and McCormick Theological Seminary. In certain important local matters, I have been assisted by the libraries of Knox College, Galesburg, Illinois, Illinois College, Jacksonville, Illinois, the Public Library of Peoria, Illinois, and the library of Transylvania University at Lexington, Kentucky. I also visited the Public Library of Louisville, with its historical collections, but most that I found there I had already consulted elsewhere. The New York Public Library and the Library of Columbia University supplemented my research at a few important points. The Oak Park Public Library has been constantly at my service. The Library of Berea College, Kentucky, has given me very valuable assistance in finding for me a large amount of periodical literature bearing on my study. The five great Boston libraries would have yielded me much had I come to them earlier. While the book was undergoing revision, I visited the Athenaeum, the Massachusetts State, the Boston Public, the Massachusetts Historical, and the Harvard University libraries. It was gratifying to discover that even in the last named of these, enriched as it is with the collections of Charles Sumner, Thomas Wentworth Higginson, and the Lincoln collection of my friend Alonzo Rothschild, author of "Lincoln, Master of Men," there was practically nothing relating to this subject which I had not already seen and examined. In the Massachusetts Historical Library, however, I discovered some manuscripts, and that quite unexpectedly, which afford me much aid in a collateral study. In addition to the foregoing, I have my own Lincoln library, which, while a working collection rather than one of incunabula, and modest in size as compared with some that I have used, is still not small. The Bibliography at the end of the volume is virtually a catalogue of my own Lincoln books.