He returned from Europe bringing his sheaves with him. He resolved to devote himself to the study and practice of jurisprudence, to avoid political strife and political office, hoping that he might, perhaps, at some future time, succeed to the chair of Judge Story at Harvard. He kept up his habit of incessant labor. He contributed to the reviews and newspapers a few essays on literature and jurisprudence, and some obituary notices of deceased friends. He became interested in prison discipline and in the cause of peace. In January, 1846, he engaged in an earnest debate in the Prison Discipline Society, in which he favored the system of separate imprisonment for criminals, and maintained his side with great power. July 4, 1845, he delivered in Boston the oration printed in these volumes entitled, "The True Grandeur of Nations," which was declared by Richard Cobden to be the most powerful contribution to the cause of peace made by any modern writer. August 27, 1846, he delivered before the Phi Beta Kappa Society, at Harvard, his oration entitled, "The Scholar, The Jurist, The Artist, The Philanthropist," in which, in the form of eulogies of his four friends, Pickering, Story, Allston, and Channing, he set forth with masterly eloquence the beauties of the virtues of which they were shining examples. But he could not remain an indifferent spectator of the great contest then going on between freedom and slavery for the possession of the vast territory between the Mississippi and the Pacific. His first public speech against slavery, printed in these volumes, was delivered November 4, 1845. June 28, 1848, he was present at the meeting in Worcester, where the Free Soil party, afterward the Republican party, was founded, and from that time was recognized in Massachusetts, and very largely throughout the country, as the most eloquent leader and champion of the political movement against slavery. He was elected to the seat of Daniel Webster, in the Senate of the United States, April 24, 1851, and took the oath of office December 1, 1851. The history of his career from that time to his death, the history of the great party he helped to found, the history of liberty in the United States, are almost identical. "The record of the cause he loved Is the best record of its friend." It was impossible for Charles Sumner to keep aloof from the great contest for which he was the best equipped champion alive, or to decline to obey the voice of the beloved commonwealth commanding him to take his place in the front and heat of the battle. He had every quality of soul and intellect, every accomplishment, every equipment, needed to fit him for that lofty leadership. Emerson said of him that he had the whitest soul he ever knew. In such warfare no armor of proof is like the defence of absolute integrity, no temper of the sword is like that of perfect purity.