I’ve answered this question before, and here is the passage:
“When in the Course of human events, it becomes necessary for one people to
dissolve the political bands which have connected them with another, and to
assume among the powers of the earth, the separate and equal station to which
the Laws of Nature and of Nature's God entitlethem, a decent respect to the
opinions of mankind requires that they should declare the causes which impel
them to the separation.”
The passage from the Declaration of Independence that directly
states the purpose of the document is declare the causes.
To add, John Trumbull's Declaration of Independence is a 12-by-18-foot
oil-on-canvas painting in the United States Capitol Rotunda that depicts the
presentation of the draft of the Declaration of Independence to Congress.
