Strictly speaking, the Philadelphia Convention lacked the mandate to draft a Constitution to replace the inadequate Articles of Confederation. Urged on, by vision and necessity, the Convention not only drafted a new federal and democratic Constitution setting up the United States of America, but it included a crucial provision on its entry into force.
The Constitution of the United States of America, as agreed upon by the Convention, September 17, 1787, Article VII:
The Ratification of the Conventions of nine States shall be sufficient for the Establishment of this Constitution between the States so ratifying the Same.
Just a few words and a few defining moments make the difference between success and failure of global proportions.