There are six propositions identified in the US Constitution preamble. These are:
-forming an improved nation and government
-creating a system of justice
-maintaining peace within the nation
-have a method of defense for external disputes
-promote the well-being of citizens
-provide liberty to all citizens
They are arranged in a manner where it begins and ends with more obscure propositions about better union, well-being and liberty. In the middle, they stated clearer and specific measures which call for justice, peace and a method of defense when peace fails. The order makes a logical text structure.
Hope this helps.