After the accomplishment of his desires in relation to South America, he again reverted to his favorite policy; favorite, because he saw its intimate connection with the growth and prosperity of his country, as calculated to develope her vast resources, and to pour into her lap the blessings of a virtuous and free people. The formation of Mr. Clay’s attachment to internal improvements and domestic manufactures, is coeval with his entrance into congress; and when matters demanding immediate attention had been disposed of, he would bring them forward, and labor to make the conviction of their importance sink deep into the heart of the nation. When Mr. Madison returned, with his objections, the bill appropriating the bonus of the United States bank for purposes of internal improvements, Mr. Clay expressed his astonishment. He had confidently calculated on its receiving the signature of the president; for he had particularly invited the attention of congress, in his message, ‘to the expediency of exercising their existing powers, and where necessary, of resorting to the prescribed mode of enlarging them, in order to effectuate a comprehensive system of roads and canals, such as will have the effect of drawing more closely together every part of our country, by promoting intercourse and improvements, and by increasing the share of every part in the common stock of national prosperity.’ Mr. Clay had heard, through the medium of uncertain rumor, that Mr. Madison designed to veto the bill, whereupon he sent him a communication, requesting him, if he entertained any constitutional scruples about signing it to let the whole matter rest and pass over to his successor for action. The president, however, took a different view of the subject, and on the third of March, returned the bill. On the following day, Mr. Monroe was inducted into his office, who, it was conjectured, prior to seeing Mr. Madison’s veto-message, had prepared his inaugural address in such a manner as to recommend, in strong terms, the policy of promoting internal improvements, but that, on reading Mr. Madison’s objections to the bill, he changed his opinion. It was thought he was led to do so partly from fear, and partly from a desire to conform his views with those of his predecessor. Subsequently he stated that a careful investigation had conducted him to the conclusion, that the power of making internal improvements was not vested in congress, and that to clothe that body with it, an amendment of the constitution was requisite. Opposition such as this policy had encountered, from so exalted a source as that of three chief magistrates, (Messrs. Jefferson, Madison and Monroe,) would have appalled a mind of ordinary strength and perseverance; but Mr. Clay was one who never formed an opinion with precipitancy, but only when, by the most diligent inquiry, he had established a foundation for it in reason and philosophy. Erected upon this basis, he would adhere to it, though confronted by the combined opposition of the world. A compromise of principle he was a stranger to. Nothing disheartened, therefore, by the magnitude of the obstacles opposed to his progress in advocating his favorite measures, by those high in authority, he seemed to gather fresh energy from every new one that he encountered. In March, 1818, a resolution was submitted to the house, declaring that congress had power to construct military post-roads and canals, and also to appropriate money for that object. The opposition to this presented a formidable array of strength, and brought forward every objection that political ingenuity could devise. Mr. Clay did not deem it advisable to consume the time of the house in examining in detail any except those denominated _constitutional_. His whole aim, therefore, was to prove that the power alleged in the resolution, was derivable from the constitution; and this he accomplished in the most convincing manner. In construing this instrument, he observed the same rules which governed his action in relation to the bank bill of 1816. He maintained that every power, which _appeared necessary and proper_, to secure the lawful exercise of constitutional rights, _was fairly impliable_, and that this _necessity and propriety_ must be determined by the discretion of those who exercised it, ‘under all the responsibility of a solemn oath,’ and the knowledge that they were the subjects of those laws that they passed, and that they were amenable to the _people_, who held in reserve the right to resist tyrannic usurpation. Mr. Clay argued that the power to _establish_ post-roads, expressly specified in the constitution, involved the power to _construct_ them.