A third compromise sprang from the conflicting interests of the commercial and the planting states. The planting states wanted a provision forbidding Congress to pass navigation acts, except by a two-thirds vote, and forbidding any tax on exports; three states also wished to import slaves for use on their plantations. The free commercial states wanted Congress to pass navigation laws, and also wanted the slave trade stopped, because of the three-fifths rule. The result was an agreement that the importation of slaves should not be forbidden by Congress before 1808, and that Congress might pass navigation acts, and that exports should never be taxed. %178. The Election of President.%--Another feature of the Virginia plan was the provision for a President whose business it should be to see that the acts of Congress were duly enforced or executed. But when the question arose, How shall he be chosen? all manner of suggestions were made. Some said by the governors of the states; some, by the United States Senate; some, by the state legislatures; some, by a body of electors chosen for that purpose. When at last it was decided to have a body of electors, the difficulty was to determine the manner of electing the electors. On this no agreement could be reached; so the convention ordered that the legislature of each state should have as many electors of the President as it had senators and representatives in Congress, and that these men should be appointed in such way as the legislatures of the states saw fit to prescribe. %179. Sources of the Constitution.%--An examination of the Constitution shows that some of its features were new; that some were drawn from the experience of the states under the Confederation; and that others were borrowed from the various state constitutions. Among those taken from state constitutions are such names as President, Senate, House of Representatives, and such provisions as that for a census, for the veto, for the retirement of one third of the Senate every two years, that money bills shall originate in the House, for impeachment, and for what we call the annual message.[1] [Footnote 1: On the sources of the Constitution, read "The First Century of the Constitution" in _New Princeton Review,_ September, 1887, pp. 175-190.]