The agreed parameters of a Joint Comprehensive Plan of Action on Iran’s nuclear program that were reached Thursday between the Islamic Republic and the five permanent members of the United Nations Security Council plus Germany represent a monumental achievement that affirms the power of reason and diplomacy over the ravages of fear and warfare.

The technical details of the complex understanding remain to be completed. For now, though, the lasting significant aspects of this development are about the past and the future: the past being the bold leadership that Iran and the United States have shown in launching and advancing diplomatic negotiations, and the future being about the potential significant regional changes that will follow the implementation of a full agreement.

I will assess in a separate column the potential positive changes in the region that this agreement could trigger. Here I would note enthusiastically the historic lessons to be learned about the power of negotiations over threats. More specifically, this is about the capacity of serious and responsible leaders to advance a diplomatic negotiation by having the courage and confidence to change positions they had long held, but that had become untenable over time. It took serious courage, for example, for the United States and the others with it to finally accept that Iran has the right to enrich uranium for peaceful purposes, under international inspections and safeguards.

The U.S. and Israel in particular had for years fervently opposed allowing Iran to maintain any enrichment facilities that would allow it to produce its own nuclear fuel. Israel stuck to its extremist position, but the U.S. came to terms with the reality that threats, sanctions and repeated talk of war had not slowed down Iran’s uranium enrichment program, but in fact only saw it expand. The tacit U.S. acknowledgment in 2013 that Iran would maintain its enrichment capabilities – because it had already achieved them and these could not be bombed away – opened the door for serious negotiations.

Toning down the constant threats of American military attacks against Iran also helped to open that door. Never mind that Washington continues until this day to use offensive language about Iran that presupposes Tehran’s deception and mendacity in conducting its policies and negotiations, treating Iran like one would a delinquent offender who has to be nursed back into a normal life under strict police supervision. Iran understood that this was primarily for domestic U.S. and Israeli consumption, where racist language against Arabs, Iranians and others in this region is routine.

Iran largely ignored the offensive tone, in favor of focusing on the substance of the talks that had to allow Tehran two things: to continue its nuclear program, including enriching uranium and conducting research and development work, for verifiably peaceful purposes; and, simultaneously to find a solution lifting the sanctions against Iran. The Americans and their partners eventually acknowledged these two demands.

The Iranians also had to make some significant changes in their positions. These included issues like the length of the agreement, the nature of inspections and monitoring, the pace of sanctions reduction and the magnitude and kinds of nuclear materials production facilities. Iranian leaders mustered significant humility and courage to accept the key demands of the P5+1 states that are supposed to prevent Iran from achieving a speedy breakthrough to producing a nuclear bomb.

Iran made such big concessions for two important reasons, or principles, that others in conflict situations can learn from: reciprocity and respect. When the Americans and their colleagues started dealing with Iran on the basis that concessions would be made by both sides, and that such concessions would happen on the basis of respecting the rights of all parties equally, breakthroughs started to happen.

The obvious agreement that could have been identified a decade ago finally moved ahead toward consummation in the past year, with all negotiators getting their key demands. Israel has been left in the dust to a large extent for now. The human and political sides of reaching an agreement have been much tougher than the technical details. Rarely in modern history have we seen such decisive statesmanship, reflecting a rare combination of realism, honesty, humility, boldness and foresighted leadership. These attributes rarely all gather in the chests of individual human beings, but they have done so here.

We have seen such history-making leadership in several other episodes in the past two generations: When the U.S. and China reconciled; when the South African Apartheid system was transformed into democratic majority rule; when leaders in Northern Ireland ended their conflict and shared power democratically; when Polish leaders and opposition members negotiated a transition away from Communist authoritarianism toward an elected government; and when Mikhail Gorbachev saw the bankruptcy of Soviet authoritarianism and initiated a transition to something better for his people.

The men and women who conducted this diplomacy join a special group of leaders and officials who deserve great thanks and appreciation for reminding us of the immense power of negotiating on the basis of reciprocity and respect.