The original question had to be edited. I think that the system of checks and balances is one way in which the goal of "to form a more perfect union" is achieved." The form of government in which one branch of government is limited by the other two helps to establish the goal of "forming a more perfect union" through its assurance that one branch could not subvert the entire democratic process. The notion of government being able to rest on the responsibility of each branch is essential to idea that the framers embedded in forming a more perfect union. Government is seen as an experiment that always "tries to get it right," and in this process mistakes can be recognized by the other two branches. This limited form of government that demands cooperation between the branches helps to ensure that forming a more perfect union is something practiced in the realistic life of American government.
The framers understood that the essential nature of "forming a more perfect union" was one in which government recognizes its mistakes and seeks to make right that which is wrong. It is here in which the democratic experiment finds a home. The ability for amendments to be added helps to achieve this goal. For example, the framers understood that the first ten amendments would not be the only ones to the Constitution. The fact that the framers developed a method to amend the Constitution represents the historical promise commitment to forming a more perfect union. The ability for the Constitution to have amendments added that could bring more people into the political process such as the 13th, 14th, 15th, 19th, and 26th Amendments or to even recognize when mistakes are made, such as the 21st repealing the 18th, are a part of this process. In this reality, it becomes clear that the framers saw that process of amending the Constitution as one in which the promises and possibilities of forming a more perfect union are fully realized.