In work and study time slipped away. He was the same cheery companion as of old, much sought after by his friends, but now more often to be found in his office surrounded by law-books and papers than had been the case before his term in Congress. His interest in politics seemed almost to have ceased when, in 1854, something happened to rouse that and his sense of right and justice as they had never been roused before. This was the repeal of the "Missouri Compromise," a law passed by Congress in the year 1820, allowing Missouri to enter the Union as a slave State, but positively forbidding slavery in all other territory of the United States lying north of latitude 36 degrees 30 minutes, which was the southern boundary-line of Missouri. Up to that time the Southern States, where slavery was lawful, had been as wealthy and quite as powerful in politics as the Northern or free States. The great unoccupied territory lying to the west, which, in years to come, was sure to be filled with people and made into new States, lay, however, mostly north of 36 degrees 30 minutes; and it was easy to see that as new free States came one after the other into the Union the importance of the South must grow less and less, because there was little or no territory left out of which slave States could be made to offset them. The South therefore had been anxious to have the Missouri Compromise repealed. The people of the North, on the other hand, were not all wise or disinterested in their way of attacking slavery. As always happens, self-interest and moral purpose mingled on both sides; but, as a whole, it may be said that they wished to get rid of slavery because they felt it to be wrong, and totally out of place in a country devoted to freedom and liberty. The quarrel between them was as old as the nation, and it had been gaining steadily in intensity. At first only a few persons in each section had been really interested. By the year 1850 it had come to be a question of much greater moment, and during the ten years that followed was to increase in bitterness until it absorbed the thoughts of the entire people, and plunged the country into a terrible civil war.