Why is it important that the Declaration tells from where we get our rights?

That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, –That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on.  In other words, “to declare the causes which impel them to the separation. ... The list of 27 complaints against King George III constitute the proof of the right to rebellion. ... Join our fight, reads the subtext, and you join humankind's fight ... The most important and dramatic statement comes near the end.