Rejuvenated, perhaps, by his pivotal role as opposition leader in guaranteeing Ariel Sharon the parliamentary majority the Prime Minister's own deeply divided Likud party would otherwise deny him, Shimon Peres was optimistic when he met foreign journalists this week.

Rejuvenated, perhaps, by his pivotal role as opposition leader in guaranteeing Ariel Sharon the parliamentary majority the Prime Minister's own deeply divided Likud party would otherwise deny him, Shimon Peres was optimistic when he met foreign journalists this week.

Listening to him, it was not hard to imagine that the long march to peace had at last begun again. Dismissing widespread claims that the internationally agreed "road-map" to peace was dead, he said that there was "no person who can dismantle it".

And the Labour leader insisted that the plan to disengage from Gaza, finally approved by the Knesset last night, was the "beginning of a journey to a permanent solution".

A key question for the Middle East after last night's vote is whether the octogenarian veteran of the Oslo Accords is right or whether Mr Sharon will now draw a red line having achieved the minimum required to get the Americans and the rest of the international community ­ to use the phrase of his close lieutenant Dov Weisglass ­ "off our case".

That last night's vote will presage a welter of speculation about the future of Mr Sharon himself is a safe bet ­ paradoxically, since on an important level last night's victory was an undoubted personal triumph.

But he is at odds with half of his party, in effect leading a minority government, and regarded by the settlers themselves as a traitor to the cause he once so zealously espoused. All sorts of permutations will be canvassed ­ that he will still be obliged to hold the referendum that he has resisted, that he will be forced out, perhaps by a defeat on the annual budget, and that he will be replaced as Likud leader. Any of these scenarios is possible; he could certainly do without the resignations threatened last night by ministers led by Benjamin Netanyahu; but Mr Sharon did not blink when they delivered their ultimatum before last night's vote. The dissident ministers may even have blown their best chance to stop disengagement in its tracks.

Mr Sharon is a shrewd survivor, and his political obituary has been written many times.

For one thing, Mr Peres's own party, faced with the choice of bringing down Mr Sharon or seeing the withdrawal of 8,000 settlers from Gaza next year, shows every sign of opting for the latter.

But in any case the meaning of last night's vote goes well beyond the labyrinthine permutations of internal Israeli politics. One analysis, shared between Mr Peres, (just) to the left of the political centre, and Mr Sharon's most vociferous critics on the far right ­ including Mr Sharon's old friend the Knesset Speaker Reuven Rivlin ­ is that the Gaza disengagement plan is the beginning of the much bigger withdrawal from the occupied territory in the West Bank and a path to the creation of a viable Palestinian state.

The other, proffered by many Palestinians, is that it is quite the opposite: a concession that will allow the Sharon government to consolidate its grip on the occupied West Bank, including almost all but the most remote settlements there. Proponents of this view have powerful evidence ­ a Haaretz interview earlier this month by Mr Weisglass, who hatched the withdrawal plan with Mr Sharon, in which he said it was the "formaldehyde" that would "freeze" the peace process and which ensured that "out of 240,000, 190,000 settlers will not be moved from their place".

In his Knesset speech on Monday Mr Sharon gave conflicting signals. On the one hand he said in terms that could have been dictated ­ and perhaps were ­ by a Washington perturbed by the Weisglass interview, that disengagement was not a substitute for negotiations, but a move made when negotiations were impossible. On the other he said disengagement would strengthen Israel's hold over territory essential to its existence, which it is hard to believe does not refer to the West Bank.

Yet even that should not obscure what remains a historic event, the first reverse of relentless Jewish settlement, illegal under international law, in territory occupied by Israel in the war of 1967. The right-wing extreme, the bearers of the torch of a greater Israel running from the river Jordan to the Mediterranean, can no longer be sure of prevailing over a majority that pays dearly for the settlements, financially and in the lives of soldiers, and who want to see Gaza evacuated.

Mr Peres's view may well be over-optimistic in the short term but last night's vote has created a momentous precedent.