Which phrase in this passage from the declaration of independence directly states the purpose of the document?

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.