what does jefferson state directly as the reason this declaration had to be written

Jefferson states directly that the Declaration had to be written because the American colonies were compelled to declare and explain why they were breaking their political connection with Britain, once separation had become necessary. In the opening sentence, he says that when one people must dissolve the political bonds with another, “a decent respect to the opinions of mankind” requires that they declare the causes which impel them to the separation. In simpler words: the reason this declaration had to be written is to formally state and justify the causes for separating from Great Britain.