US government's authority comes from the consent of the people it governs.Governments are instituted among men,deriving their just powers from the consent of the governed.
I would say this part...
"Secure the blessings of liberty, to ourselves and our prosperity"
Jews were slaves in Egypt
The Israelites had been in Egypt for generations, but they had become so numerous the Pharaoh freard their presence. He thought the Israelites would turn against the Egyptians so he forced them to become his slaves
