The external relations of a people may be compared to those of private individuals, and they cannot be advantageously maintained without the agency of a single head of a Government. The exclusive right of making peace and war, of concluding treaties of commerce, of raising armies, and equipping fleets, was granted to the Union. *h The necessity of a national Government was less imperiously felt in the conduct of the internal policy of society; but there are certain general interests which can only be attended to with advantage by a general authority. The Union was invested with the power of controlling the monetary system, of directing the post office, and of opening the great roads which were to establish a communication between the different parts of the country. *i The independence of the Government of each State was formally recognized in its sphere; nevertheless, the Federal Government was authorized to interfere in the internal affairs of the States *j in a few predetermined cases, in which an indiscreet abuse of their independence might compromise the security of the Union at large. Thus, whilst the power of modifying and changing their legislation at pleasure was preserved in all the republics, they were forbidden to enact ex post facto laws, or to create a class of nobles in their community. *k Lastly, as it was necessary that the Federal Government should be able to fulfil its engagements, it was endowed with an unlimited power of levying taxes. *l h [ See Constitution, sect. 8; “Federalist,” Nos. 41 and 42; Kent’s “Commentaries,” vol. i. p. 207; Story, pp. 358-382; Ibid. pp. 409-426.] i [ Several other privileges of the same kind exist, such as that which empowers the Union to legislate on bankruptcy, to grant patents, and other matters in which its intervention is clearly necessary.] j [ Even in these cases its interference is indirect. The Union interferes by means of the tribunals, as will be hereafter shown.] k [ Federal Constitution, sect. 10, art. I.] l [ Constitution, sects. 8, 9, and 10; “Federalist,” Nos. 30-36, inclusive, and 41-44; Kent’s “Commentaries,” vol. i. pp. 207 and 381; Story, pp. 329 and 514.] In examining the balance of power as established by the Federal Constitution; in remarking on the one hand the portion of sovereignty which has been reserved to the several States, and on the other the share of power which the Union has assumed, it is evident that the Federal legislators entertained the clearest and most accurate notions on the nature of the centralization of government. The United States form not only a republic, but a confederation; nevertheless the authority of the nation is more central than it was in several of the monarchies of Europe when the American Constitution was formed. Take, for instance, the two following examples.