At that time no statesmen, North or South, had fully grasped the slavery question. Even Mr. Calhoun once seemed to have no doubt as to the authority of Congress to exclude slavery from the Territories, but he was decided enough in his opposition when he saw that it involved an irreconcilable conflict of interests,--that slavery and freedom are antagonistic ideas, concerning which there can be no genuine compromise. "There may be compromises," says Von Holst, "with regard to measures, but never between principles." And slavery, when the Missouri Compromise was started, was looked upon as a measure rather than as a principle, concerning which few statesmen had thought deeply. As the agitation increased, measures were lost sight of in principles. The compromise by which Missouri was admitted as a slave State, while slavery should be excluded from all territory outside of it north of 36° 30', was a temporary measure of expediency, and at that period was probably a wise one; since, if slavery had been excluded from Missouri, there might have been a dissolution of the Union. The preservation of the Union was the dearest object to the heart of Clay, who was genuinely and thoroughly patriotic. Herein he doubtless rendered a great public service, and proved himself to be a broad-minded statesman. To effect this compromise Clay had put forth all his energies, not only in eloquent speeches and tireless labors in committees and a series of parliamentary devices for harmonizing the strife, but in innumerable interviews with individuals. In 1820, Clay retired to private life in order to retrieve his fortunes by practice at the bar. Few men without either a professional or a private income can afford a long-continued public service. Although the members of Congress were paid, the pay was not large enough,--only eight dollars a day at that time. But Clay's interval of rest was soon cut short. In three years he was again elected to the House of Representatives, and in December, 1823, was promptly chosen Speaker by a large majority. He had now recovered his popularity, and was generally spoken of as "the great pacificator."