Kingship is beneficial because it is the rule of one person. Aquinas states that the correct and most useful way to carry out an objective is "when it is lead to its appropriate end" (15). The incorrect way would be the opposite--to lead something to an inappropriate end, or not to lead it to an end at all. In light of this definition, the most effective government would lead the people to their appropriate end, which Aquinas believes is unity. In this sense, Aquinas believes that obviously something that "is itself one can promote unity better than that which is a plurality" (17). This may not seem quite so obvious to anyone else, and his analogy between unity and heat may seem a little vague, but Aquinas still makes a valid point in that creating a government promoting unity is more difficult when more people are involved. This is simply because of the number of ideas and interpretations present within a group that are not present under the rule of one.
Aquinas also argues that kingship, or the good, just monarchy, is preferable because it is present in nature. He likens the king to God, because naturally God is the "Ruler over all" (17). It is therefore natural for one man to rule many, as long as he is leading the people to their appropriate end, which is unity. The king should be "a shepherd who seeks...not his own benefit" (16), which is an instance of government represented by nature. Aquinas believes that as "art imitates nature" (18), so should politics, and the best art is that which best imitates nature. In this sense, the best