Does he know what is the state of the nation better than Congress?

Yes; his office is such that he is better situated for knowing it. Members of Congress reside in and represent only one State, but the President occupies a position of national authority. It is the duty of all officers below him, to submit reports of the various affairs in which they are employed, to one or other of the Heads of Departments, and these lay all the information and intelligence they thus obtain, before the President as resources to direct and assist him in the many and great duties he has to perform. He is, therefore, of all other persons, best acquainted with the general concerns of the nation.