A key belief of John Locke was the idea of THE SOCIAL CONTRACT.
Explanation:
According to Locke idea of a "social contract,"  a government's power to govern comes from the consent of the people themselves -- those who are to be governed.  This was a change from the previous ideas of "divine right monarchy" -- that a king ruled because God appointed him to be the ruler.  Locke repudiated the views of divine right monarchy in his First Treatise on Civil Government (1690).  In his Second Treatise on Civil Government (1690), Locke argued for the rights of the people to create their own governments according to their own desires and for the sake of protecting their own life, liberty, and property.
Here's a passage from Locke's Second Treatise, which asserts that a government only has its power by the consent of the people who live under that government:
No government can have a right to obedience from a people who have not freely consented to it; which they can never be supposed to do, till either they are put in a full state of liberty to choose their government and governors, or at least till they have such standing laws, to which they have by themselves or their representatives given their free consent, and also till they are allowed their due property, which is so to be proprietors of what they have, that no body can take away any part of it without their own consent, without which, men under any government are not in the state of freemen, but are direct slaves under the force of war.
