King was a minister criticized by clergymen, so he tried to justify his cause by paraphrasing the words of Thomas Aquinas, a notable interpreter of God's order on earth. He uses this allusion because he wants to underline the crucial difference between just and unjust law, that has been confirmed by one of the highest intellectual authorities in the fields of philosophy and religion. King provides a religious justification for the concept of nonviolent resistance.
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According to the passage, windmills aided the growth of the country of Holland J. by pumping seawater, the Dutch flooded coastal bogs in order to improve ship travel.