The book itself is not in the Lincoln Home at Springfield, nor is it in the Oldroyd Collection at Washington, in one of which places I hoped that it might be found. Neither the librarian of the Illinois Historical Society in Springfield, nor Mr. Barker, the painstaking and discriminating collector and vendor of Lincoln books in Springfield, had ever noticed the title in Herndon's book, though both were at once impressed with its significance when I called it to their attention. The material in Herndon's lectures on Lincoln is pretty well absorbed in his book, and quoted in this volume; but there are some interesting additional details in Herndon's letters. In these, answering specific questions or replying to definite statements, he now and then added a statement which was not later included in his book, but which has present interest and in some cases value. The following is an excerpt from a letter of Herndon to John E. Remsburg, and bears in an important way on Lincoln's use of _Vestiges of Creation_: "I had an excellent private library, probably the best in the city for admired books. To this library Mr. Lincoln had, as a matter of course, full and free access at all times. I purchased such books as Locke, Kant, Fichte, Lewes; Sir William Hamilton's _Discussions of Philosophy_; Spencer's _First Principles_, _Social Studies_, etc.; Buckle's _History of Civilization_, and Lecky's _History of Rationalism_. I also possessed the works of Parker, Paine, Emerson and Strauss; Gregg's _Creed of Christendom_, McNaught on _Inspiration_, Volney's _Ruins_, Feuerbach's _Essence of Christianity_, and other works on Infidelity. Mr. Lincoln read some of these works. About the year 1843[44] he borrowed the _Vestiges of Creation_ of Mr. James W. Keys, of this city, and read it carefully. He subsequently read the sixth edition of this work, which I loaned him. He adopted the progressive and development theory as taught more or less directly in that work. He despised speculation, especially in the metaphysical world. He was purely a practical man."--REMSBURG: _Six Historic Americans_, pp. 114-15. As already stated Dr. Smith's book _The Christian's Defence_ is excessively rare. The edition was small; the argument which it contained was modified with the progress of discovery; there was little to keep in circulation the few copies of the book that survived. They have nearly all disappeared. I have searched the second-hand shops of the principal cities and the dusty duplicates of libraries with repeated disappointment. For this reason, I have carried a complete analysis of the book into the Appendix of this volume; for few who read the present volume will be able to see the book itself.