French statesmen Richelieu has formulated ideas on diplomacy like some authors in Italy. His theory of diplomacy can be derived from his Political Testament, in which he has penned political advice for Louis XIII. Having become the French prime minister in an age of continuous wars, Richelieu’s main concern was to establish peace and carry out peaceful relations with other states. The first significant diplomatic writer of the twentieth century is Ernest Satow. Satow owes his reputation in diplomatic theory to his book Guide to Diplomatic Practice, which was the first remarkable book in English language about the theory and practice of diplomacy when it was published in 1917. Another British diplomat who has contributed to diplomatic theory is Harold Nicolson. Like Satow he combined his experience with the history of diplomacy. In his book titled Diplomacy, which was published in 1939, a whole chapter is dedicated to the development of diplomatic theory. Another important writer who should be mentioned is Hans Morgenthau, who is considered the founder of international relations. Morgenthau’s theory, which he portrayed in his 1948 book Politics Among Nations, can also be read as a contribution to the theory of diplomacy although not dedicated to it. Morgenthau sees the quality of diplomacy as the most important of all the factors which make the power of a nation, since it is diplomacy that brings the different elements of national power to bear with maximum effect upon those points in the international situation which concern the national interest most directly. The last diplomatist/writer to be discussed in this chapter is Henry Kissinger. Kissinger’s famous work titled Diplomacy can actually be read as a history book and on many occasions he has been described as a historian. He does believe that international politics cannot be seized by only theoretical approach and for this reason the study of history is crucial. The correct answer is Choice D.