Since there can be such a wide gap between the ideals of the United Nations and the harsh reality of world affairs, it is perhaps just as well that the UN Secretary-General, Mr Kofi Annan, has a sense of humour.
Addressing college students in Washington last May, he quipped that the world was made up of optimists and pessimists: "In the end they are both wrong, but the optimist is happier."
It is Mr Annan's job to be an optimist and, in that spirit, he has outlined a programme of action for the Millennium Summit, to take place at UN headquarters in New York on September 6th-8th. All 188 members have been invited to send their heads of state or government, making it probably the largest gathering of political leaders yet. The Taoiseach, Mr Ahern, will be among the attendance but with such a long list of contributors, his address to the summit will be limited to five minutes. He is expected to make a more detailed and comprehensive speech to one of the New York-based foreign policy groups, under the title, "Ireland in the World".
The purpose of the summit is to consider how to strengthen the role of the UN to meet the challenges of the 21st century. In Mr Annan's words, it offers "a timely opportunity for the world's leaders to look beyond their pressing daily concerns and consider what kind of United Nations they can envision and will support in the new century".
If all the challenges could be encapsulated in a single word, it would be "globalisation". The world is interconnected as never before, thanks partly to the revolution in communications technology. There are dangers but there are also opportunities for prosperity to reach unprecedented levels - for some. Mr Annan asks: "How can we say that the half of the human race which has yet to make or receive a telephone call, let alone use a computer, is taking part in globalisation?"
The main challenge facing the world leaders gathering in New York is to make globalisation mean more than just bigger markets: to devise and impose a set of rules and shared social objectives so that the world's people are not left at the mercy of unpredictable economic forces.
Mr Annan says that priority must be given to three basic freedoms - "freedom from want, freedom from fear, and the freedom of future generations to sustain their lives on this planet". A billion human beings are struggling to survive on less than one US dollar (about 86p) a day; wars between states may be less frequent, but in the last decade internal conflicts have claimed more than five million lives; the nuclear threat continues to overshadow the world; and the environment is threatened as never before. As Mr Annan puts it, "We are plundering our children's heritage to pay for our present unsustainable practices."
He has asked the advanced member-states in particular to grant free access to their markets for goods produced in poor countries; to be more generous in respect of debt relief and development assistance; and to make special provision for the needs of the African continent.
THE Taoiseach is expected to touch on these themes in his two speeches, especially the responsibility of advanced countries to the developing world. He will highlight the need for action to deal with the AIDS crisis in southern Africa: the Government has decided to allocate extra resources for this, and measures to combat the disease are being made an integral part of the programme of Irish assistance to developing countries.
Mr Ahern will also stress the importance of UN peacekeeping operations, an area where Ireland has made a distinctive contribution. He is bound to mention the success of the Belfast Agreement which President Clinton and others have held up as a model for the resolution of other conflicts.
On UN peace operations, recommendations are being prepared for the summit by a high-level panel established by Mr Annan. "National sovereignty offers vital protection to small and weak states, but it should not be a shield for crimes against humanity," he has said.
A debate has begun around the concept of "humanitarian intervention". Writing in the Trocaire Development Review last year, the former secretary general of the Department of Foreign Affairs, Mr Noel Dorr, said the concept had not yet been adequately defined, nor had any rules for its application been agreed.
"The context for this discussion is set by the appalling events in Rwanda, Bosnia, Kosovo, East Timor and elsewhere. Many countries are coming to believe that there is a moral imperative on the international community to act in such cases where there is extreme suffering and gross and systematic violations of human rights verging on genocide. The question is whether this imperative should prevail over traditional concepts of state sovereignty and non-intervention, to which many countries also hold strongly," Mr Dorr wrote.
Article 2.7 of the UN Charter explicitly precludes the organisation from intervening through the Security Council in matters which are essentially within the domestic jurisdiction of any state. Although the article is not always strictly construed, it broadly prevents the council from responding to situations within the frontiers of a state in which extreme suffering is caused to large numbers of people and the concepts of humanity and decency which underlie the existence of the UN are flouted.
Dorr asks: "Is there any way to reconcile what seems to be a clear moral imperative to act in face of gross atrocities with the structures of international legitimacy?"
Amendment of the UN Charter to permit humanitarian intervention would not be easy to achieve and attempts to apply the principle would sooner or later come up against the veto power given to the five permanent members of the Security Council - the US, Russia, China, France and the UK.
Nevertheless, if the UN is to retain relevance, such issues must be tackled, and the debate is likely to be brought forward to some extent at the Millennium Summit.
Ireland is actively campaigning for one of the non-permanent seats on the Security Council and, if successful, will probably have to contend with internal conflicts which cry out for the kind of action that the UN is in principle forbidden to undertake.
Partly because of its apparent powerlessness in some modern conflicts, there is a fair amount of public cynicism about the UN and, even more, the often windy and insincere declarations of political leaders. However in the absence of an alternative structure for the conduct of international relations, and given the depth and scale of the problems confronting the modern world, member-states have no option but to refine and improve the international body which emerged from the ruins of war in 1945 to give practical effect to the motto, "Never again."