George Washington
If in the opinion of the people, the distribution or modification of the constitutional powers be in any particular wrong, let it be corrected by an amendment in the way in which the Constitution designates. But let there be no change by usurpation; for though this, in one instance, may be the instrument of good, it is the customary weapon by which free governments are destroyed. The precedent must always greatly overbalance in permanent evil any partial or transient benefit which the use can at any time yield. (The Farewell Address)
James Madison
A regular mode of making proper alteration has been providently inserted in the Constitution itself. It is anxiously to be wished, therefore, that no innovation may take place in other modes, one of which would be a constructive assumption of powers never meant to be granted. If the powers be deficient, the legitimate source of additional ones is always open, and ought to be resorted to. (letter to Spencer Roane, Sept. 2, 1819)
Alexander Hamilton
There never can be danger that the judges, by a series of deliberate usurpations on the authority of the legislature, would hazard the united resentment of [Congress], while this body was possessed of the means of punishing their presumption by degrading them from their stations. (The Federalist No. 81)
Joseph Story
A departure from the true import and sense of its powers is, pro tanto [to that extent], the establishment of a new Constitution. It is doing for the people what they have not chosen to do for themselves. It is usurping the functions of a legislator. (Commentaries on the Constitution of the United States, v.1, pp.325-326)