The intent of the Founding Fathers was for the Constitution to be a progressive document which would be amended as necessary to better suit the needs of future generations. In a letter to a friend in 1816, Thomas Jefferson mocked those with out common sense, such as the Modern Republicans and the Tea Partiers, who often see the Constitution as immutable.
Some men look at constitutions with sanctimonious reverence, and deem them like the arc of the covenant, too sacred to be touched; who ascribe to the men of the preceding age a wisdom more than human, and suppose what they did to be beyond amendment. Let us follow no such examples, nor weakly believe that one generation is not as capable as another of taking care of itself, and of ordering its own affairs. Each generation is as independent as the one preceding, as that was of all which had gone before.