At that early day an election to the United States Senate must have seemed to Lincoln a most brilliant political prize, the highest, perhaps, to which he then had any hopes of ever attaining. To school himself to its loss with becoming resignation, to wait hopefully during four years for another opportunity, to engage in the dangerous and difficult task of persuading his friends to leave their old and join a new political party only yet dimly foreshadowed, to watch the chances of maintaining his party leadership, furnished sufficient occupation for the leisure afforded by the necessities of his law practice. It is interesting to know that he did more; that amid the consideration of mere personal interests he was vigilantly pursuing the study of the higher phases of the great moral and political struggle on which the nation was just entering, little dreaming, however, of the part he was destined to act in it. A letter of his written to a friend in Kentucky in the following year shows us that he had nearly reached a maturity of conviction on the nature of the slavery conflict--his belief that the nation could not permanently endure half slave and half free--which he did not publicly express until the beginning of his famous senatorial campaign of 1858: [Sidenote: MS.] SPRINGFIELD, ILLS., August 15, 1855 Hon. GEO. ROBERTSON, Lexington, Ky. MY DEAR SIR: The volume you left for me has been received. I am really grateful for the honor of your kind remembrance, as well as for the book. The partial reading I have already given it has afforded me much of both pleasure and instruction. It was new to me that the exact question which led to the Missouri Compromise had arisen before it arose in regard to Missouri, and that you had taken so prominent a part in it. Your short but able and patriotic speech on that occasion has not been improved upon since by those holding the same views; and, with all the lights you then had, the views you took appear to me as very reasonable.