Leading article: A departure that heralds another age of uncertainty

Mr Peres deserves the honours that have been heaped upon him, and more will no doubt follow him into retirement. He had the vision to understand early on the imperative of peace with the Palestinians and the need for Israel to give up territory in exchange for enhanced security. The concept of "land for peace" will be forever associated with his name and that of the assassinated former prime minister, Yitzhak Rabin.

Their joint decision to embark on secret peace talks with the then Palestinian leader, Yasser Arafat, was one of the most courageous, and risky, moves made by any national leadership. Brokered by Norway, the talks resulted in the Oslo accords and a shared Nobel peace prize. Most recently, it was Mr Peres's decision to take his Labour Party into coalition with Ariel Sharon's Likud that ensured not only the survival of Mr Sharon's government, but - crucially - that the planned withdrawal from Gaza went ahead.

Becoming the junior partner in a Likud-led government required a measure of humility on Mr Peres's part that was not entirely popular with his party. But he understood that Mr Sharon's promise to hand over the Gaza strip to the Palestinian Authority served Israel's national interests and represented an opportunity that should not be allowed to slip. This was the decision of a responsible and far-sighted politician.

Of course, Mr Peres also had well-known weaknesses. He was more of a statesman than a politician. He lacked the guile necessary to operate in a political context as fickle as that of Israel today. Lionised by his own intellectual community in Israel and abroad, he nonetheless found it difficult to get his message across to the wider constituency of Israelis that he needed to win elections. The shift to the right in Israeli politics, which brought Mr Sharon to power in 2001, left the centre-left ideologically marooned and Mr Peres as a leader who seemed to have outlived his time.

Yet he remained a moderating and stabilising influence. And the consequences of his departure as Labour Party leader could be as swift as they would be unconducive to further progress in the peace process. Labour's new leader, Amir Peretz, campaigned for the job on an undertaking to take the party out of the Likud-led coalition. Whether he will actually do this will depend on a meeting with Mr Sharon this weekend. But if he does, Israel will face elections.

New elections would mean new uncertainty, just when stability and consistent national leadership are most needed. That the Palestinian Authority is also on the threshold of a parliamentary election campaign would add to the uncertainty - and the risks. Any advance in the peace process would be delayed at least until the spring.

Shimon Peres has been a pivotal figure in Israel for half a century and a force for peace in the Middle East. His countrymen, including the present Prime Minister, owe him a great deal. It is just a pity that the party leadership election he lost was so contentious and that he has found it so hard to accept defeat. With Israel's withdrawal from Gaza accomplished, Mr Peres's work is probably done. This is the time for Mr Peres to bow out gracefully and rest on his considerable laurels.