The Declaration of Independence was written because Thomas Jefferson and some of his contemporaries had had enough and weren't going to take it anymore. What exactly they had had enough of remains subject of discussion even today given the wars of independence raged since around the world and the causes of those revolutionary struggles. Be that as it may, growing disenchantment with the rule of a distant king and with the heavy-handed methods the Crown employed to maintain control over its restive colonies created growing sentiments in favor of a radical break with England. The use of Hessian mercenaries and repeated rejection of the North American colonies' requests and demands for greater political freedoms and for relief from the Crown's practicing of taxing the colonies to offset costs associated with the maintenance of empire, especially the costs of waging the French and Indian War, instilled in the colonialists a growing sense of victimization. That sense of victimization grew into a movement supportive of revolutionary change.
Thomas Jefferson's early draft of the Declaration of Independence, from which the text originally attached to the question was taken, would, of course, be replaced. Its historical significance, however, despite its elimination from the final draft, remains salient. The reason for its continued significance lies in its repeated reference to slavery:
"He has waged cruel war against human nature itself, violating it's most sacred rights of life and liberty in the persons of a distant people who never offended him, captivating and carrying them into slavery in another hemisphere, or to incure miserable death in their transportation hither. . ."
This passage, combined with his difficulty inserting "determined to keep open a market where MEN should be bought and sold" into the final text, was indicative of the divisiveness of the issue of slavery among even the most enlightened among the budding revolutionaries. Jefferson, John Adams, and Benjamin Franklin were influenced by the Enlightenment in Europe and its commitment to the rights of the individual. The conditions under which the colonials were living, with British policies becoming increasingly repressive, are reflected in the Declaration's text. A long series of predicates providing a moral and legal foundation for a break with the Crown, the Declaration represents the grievances of a people increasingly alienated from the British Empire. John Locke's "Second Treatise," in which he writes "In the state of nature, all men are equal to one another because they were created as such by God" found its place in Jefferson's draft because the Founding Fathers were influenced by the ideals of the Englightenment. Whether the conditions under which the colonials lived would be sufficient to justify open rebellion against government today could be debated. In the context of the times, however, rule from and omnipotent distant power was considered cause for revolution.