Which phrase represents the idea of self-government in the Constitution?

The phrase "We the People" represents the idea of self-government in the Constitution because it emphasizes that the authority of the government derives from the people themselves. This foundational statement, found in the Preamble of the Constitution, highlights the principle that the government is created by and for the citizens, reflecting democratic ideals. It signifies that power is vested in the populace rather than a monarch or ruling elite, which is a core tenet of self-governance. The inclusion of "the People" underscores the commitment to a government that is accountable to its citizens and operates on their behalf, thus embodying the very essence of democracy.