Barbaro’s quote appears to provide one of those rare glimpses into what the realist believes goes on behind the general depreciation of power. As an account of what diplomats do, however, it is as inaccurate and incomplete as Morgenthau’s reduction of symbolic representation to one of the lesser instruments of state power. Diplomats have never accepted that their only business is to advance the particular interests of their states. They also see themselves as working for and, therefore, representing the idea of peace. As Abba Eban notes, the words for messenger in both Greek (angelos) and Hebrew (mal’ach) have sacred, as well as secular, connotations.(13)  The use of both for messenger in general came before their use as messenger of God, but diplomats and their defenders have happily used the association with the divine to strengthen the idea that the profession serves a higher calling than, or as well as, secular power. Certainly, the idea that diplomats serve peace predates that of serving the prince. Over a half century before Barbaro, Bernard du Rosier declared that the "business of the ambassador was peace" and that he was "sacred because he acted in the general welfare."(14)  Barbaro assailed this orthodoxy because it raised "the gravest ethical problem...for theory...the possibility of a conflict between the ambassador’s duty to his prince and his duty to peace."(15) 

Secularism and statism were great spurs to the development of diplomacy as a profession, but they did not overwhelm the earlier commitment to peace. Indeed, a shared commitment to peace and saving their respective princes from themselves became hallmarks of the profession, something which diplomats could hold in common to cement their sense of corps and to gain some distance from their political leaderships. What it meant beyond this is less easy to say. In commentaries on diplomacy, it is possible to identify at least three conceptions of peace: minimalist, positivist, and transformationalist. None is a watertight category, still less a school of diplomatic thought on peace.

The minimalist school focuses on the conduct of relations by peaceful means and the peaceful resolution of disputes by negotiation. "Peace is usually better than war, and the medium of intercourse between states should not itself become a source of conflict."(16)  Seventeenth-century princes were driven to protect their interests through peace and diplomacy only after they had been exhausted by war.(17)  Ambassadors served peace when peace served, but, in the meantime, their main purpose in talking to one another was to ensure recognition from equals of the status their masters believed was their due. Britain’s ambassador to West Germany in the 1960s saw his contribution to peace in terms as describing "the other side of the story" either to his own ministers, who "were sometimes reluctant to hear it," or to foreign governments.(18)  Dobrynin saw his "fundamental task" as "helping to develop a correct and constructive dialogue between the leaders of both countries and maintaining the positive aspects of our relations wherever possible." "To both sides," he "tried to be a reassuring presence in a very strained world."(19) 

While these are practical responses to the question of what it means to serve peace, minimalism gives no more than an implicit answer to the question of what one should do when the interests of peace and those of the prince fail to coincide. For de Wicquefort, the diplomat should have an aversion to war only when war is no longer productive. Even those more obviously associated with the peace tradition in diplomatic writings are not entirely clear on this point. Du Rosier, for example, is usually interpreted as speaking in defense of the respublica christiana or God’s order in the world as it faded before the twin assaults of schismatics and rationalists. The ambassador should be regarded as sacred because "he labours for the public good" and the "speedy completion of an ambassador’s business is in the interests of all."(20)  Rather than seeking to restore God’s order, all this maybe is a case of special pleading for diplomatic immunity at a time when travel was dangerous and uncertain. Similar ambiguity can be found in the writings of François de Callières, who suggests that we will understand diplomacy better if we think of the states of Europe as joined by "all kinds of necessary commerce," as "members of one Republic" where "no considerable change can take place in any one. . .without affecting the condition, or disturbing the peace, of all the others." He even speaks of a "freemasonry of diplomacy," in which all members work for the "same end." It turns out, however, that the shared end is nothing more than "to discover what is happening."(21) 

Disappointing though this might be to those attracted by the grand rhetoric in which some writers package their practical suggestions, these suggestions go beyond the minimalist conception of diplomats as simply seeking to avoid war or prevent themselves from being a source of further tension. Whether or not states preferred peace, they had to agree upon procedures for communicating with one another, and these procedures could be arranged to minimize their potential for becoming a source of unwanted conflict. This gave rise to the positivist conception of peace, la raison de système, in which the international system or society has its own qualities or even needs which impose a certain logic, practical or prescriptive, on the behavior of its members. The sparse character of la raison de système may be contrasted with the richer respublica christiana it replaced.(22)  The latter arose out of a sense of universal law, while the former sees diplomacy as "an integral part of the minimal conditions securing the existence of international society." This amounts to little more than a corps diplomatique, which "had an independent existence, whose members were all doing the same job and who would treat each other in a civilized way even when their principles were at war."(23)  Even in war, life must go on, for diplomats at least, and this is the value which they need to represent to their princes.