But what was incendiary matter? Who should determine that point? President Jackson in 1835 had recommended Congress to pass a law prohibiting under severe penalties the circulation in the Southern States, through the mails, of incendiary publications. But this did not satisfy the Southern dictator. He denied the right of Congress to determine what publications should be or should not be excluded. He maintained that this was a matter for the States alone to decide. He would not trust postmasters, for they were officers of the United States government. It was not for them to be inquisitors, nor for the Federal government to interfere, even for the protection of a State institution, with its own judgment. He proposed instead a law forbidding Federal postmasters to deliver publications prohibited by the laws of a State, Territory, or District. In this, as in all other controverted questions, Calhoun found means to argue for the supremacy of the State and the subordination of the Union. His bill did not pass, but the force of his argument went forth into the land. How far antislavery documents had influence on the slaves themselves, it is difficult to say. They could neither read nor write; but it is remarkable that from this period a large number of slaves made their escape from the South and fled to the North, protected by philanthropists, Abolitionists, and kind-hearted-people generally. How they contrived to travel a thousand miles without money, without suitable clothing, pursued by blood-hounds and hell-hounds, hiding in the daytime in swamps, morasses, and forests, walking by night in darkness and gloom, until passed by friendly hands through "underground railroads" until they reached Canada, is a mystery. But these efforts to escape from their hard and cruel masters further intensified the exasperation of the South.