Embedded in this week’s parsha is one of the great principles of leadership. The context is this: Moses, knowing that he was not destined to lead the next generation across the Jordan into the promised land, asked God to appoint a successor. He remembered what had happened when he had been away from the Israelites for a mere 40 days. They had panicked and made a Golden Calf. Even when he was present, there were times of strife, and in recent memory, the rebellion on the part of Korach and others against his leadership. The possibility of rift or schism if he died without a designated successor in place was immense. So he said to God:

“May the Lord, the God who gives breath to all living things, appoint someone over this community to go out before them and come in before them, one who will lead them out and bring them in. Let the Lord’s people not be like sheep without a shepherd.” Num. 27:16-17

God duly chose Joshua, and Moses inducted him. One detail in Moses’ request, however, always puzzled me. Moses asked for a leader who would “go out before them and come in before them, one who will lead them out and bring them in.” That, surely, is saying the same thing twice. If you go out before the people, you are leading them out. If you come in before the people, you are bringing them in. Why then say the same thing twice?

The answer comes from a direct experience of leadership itself. One of the arts of leadership – and it is an art, not a science – is a sense of timing, of knowing what is possible when.

Sometimes the problem is technical. In 1981, there was a threat of a coal miners’ strike. Margaret Thatcher knew that the country had very limited supplies of coal and could not survive a prolonged strike. So she negotiated a settlement. In effect, she gave in. Afterward, and very quietly, she ordered coal stocks to be built up. The next time there was a dispute between the miners and the government –1984-1985 – there were large coal reserves. She resisted the miners and after many weeks of strike action they conceded defeat. The miners may have been right both times, or wrong both times, but in 1981 the Prime Minister knew she could not win, and in 1984 she knew she could.

A much more formidable challenge occurs when it is people, not facts, that must change. Human change is a very slow. Moses discovered this in the most dramatic way, through the episode of the spies. An entire generation lost the chance of entering the land. Born in slavery, they lacked the courage and independence of mind to face a prolonged struggle. That would take a new generation born in freedom.

If you do not challenge people, you are not a leader. But if you challenge them too far, too fast, disaster happens. First there is dissension. People start complaining. Then there are challenges to your leadership. They grow more clamorous, more dangerous. Eventually there will be a rebellion or worse.

On 13 September 1993, on the lawn of the White House, Yitzhak Rabin, Shimon Peres, and Yasser Arafat shook hands and signed a Declaration of Principles intended to carry the parties forward to a negotiated peace. Rabin’s body language that day made it clear that he had many qualms, but he continued to negotiate. Meanwhile, month by month, public disagreement within Israel grew.

Two phenomena in the summer of 1995 were particularly striking: the increasingly vituperative language being used between the factions, and several public calls to civil disobedience, suggesting that students serving in Israel’s defence forces should disobey army orders if called on to evacuate settlements as part of a peace agreement.

Calls to civil disobedience on any significant scale is a sign of a breakdown of trust in the political process and of a deep rift between the government and a section of society. Violent language in the public arena is also dangerous. It testifies to a loss of confidence in reason, persuasion, and civil debate.

On 29 September 1995 I published an article in support of Rabin and the peace process. Privately, however, I wrote to him and urged him to spend more time on winning the argument within Israel itself. You did not have to be a prophet to see the danger he was in from his fellow Jews.

The weeks went by, and I did not hear from him. Then, on Motzei Shabbat, 4 November 1995, we heard the news that he had been assassinated. I went to the funeral in Jerusalem. The next morning, Tuesday 7 November, I went to the Israeli Embassy in London to pay my condolences to the ambassador. He handed me a letter, saying, “This has just arrived for you.”

We opened it and read it together in silence. It was from Yitzhak Rabin, one of the last letters he ever wrote. It was his reply to my letter. It was three pages long, deeply moving, an eloquent restatement of his commitment to peace. We have it, framed, on the walls of my office to this day. But it was too late.

That, at critical moments, is the hardest of all leadership challenges. When times are normal, change can come slowly. But there are situations in which leadership involves getting people to change, and that is something they resist, especially when they experience change as a form of loss.

Great leaders see the need for change, but not everyone else does. People cling to the past. They feel safe in the way things were. They see the new policy as a form of betrayal. It is no accident that some of the greatest of all leaders – Lincoln, Gandhi, John F. and Robert Kennedy, Martin Luther King, Sadat, and Rabin himself – were assassinated.

A leader who fails to work for change is not a leader. But a leader who attempts too much change in too short a time will fail. That, ultimately, is why neither Moses nor his entire generation (with a handful of exceptions) were destined to enter the land. It is a problem of timing and pace, and there is no way of knowing in advance what is too fast and what too slow, but this is the challenge a leader must strive to address.

That is what Moses meant when he asked God to appoint a leader “to go out before them and come in before them, one who will lead them out and bring them in.” These were two separate requests. The first – “to go out before them and come in before them” – was for someone who would lead from the front, setting a personal example of being unafraid to face new challenges. That is the easier part.

The second request – for someone who would “lead them out and bring them in” – is harder. A leader can be so far out in front that when he turns round he sees that no one is following. He or she has gone out “before” the people, but has not “led them out.” He has led but people have not followed. His courage is not in doubt. Neither is his vision. What is wrong in this case is simply his sense of timing. His people are not yet ready.

It seems that at the end of his life Moses realised that he had been impatient, expecting people to change faster than they were capable of doing. That impatience is evident at several points in the book of Numbers, most famously when he lost his temper at Merivah, got angry with the people and struck the rock, for which he forfeited the chance of leading the people across the Jordan and into the promised land.

Leading from the front, all too often he found people not willing to follow. Realising this, it is as if he were urging his successor not to make the same mistake. Leadership is a constant battle between the changes you know must be made, and the changes people are willing to make. That is why the most visionary of leaders seem, in their lifetime, to have failed. So it was. So it always will be.

But in truth they have not failed. Their success comes when – as in the case of Moses and Joshua – others complete what they began.