Never has the old adage about a picture speaking more than a thousand words rung truer than last week. It took the image of a drowned boy off the shores of Turkey to tip the political balance. Faced with a growing clamour to act, David Cameron relented and agreed to admit more Syrian refugees.

When the Prime Minister made his announcement on Monday, he invoked the precedent of the Kindertransport, the rescue of 10,000 Jewish children from Europe on the eve of the Second World War. A few days earlier Emeritus Chief Rabbi Lord Sacks had called for a "humanitarian gesture similar to the Kindertransport" in a plea for Britain to open its gates wider.

Even before the recent outburst of public compassion, the memory of Jewish experience was spurring other Jews to raise their voice on behalf of Syrian refugees. Back in January last year, the Jewish Council for Racial Equality delivered a petition to the government to be more generous in its intake. Outside Downing Street that day, Rabbi Jeremy Gordon of the New London Synagogue remarked: "If it wasn't for the welcome this country afforded my family, we would have been caught in the horrors of the Holocaust."

While only a small, though significant, minority of the community may be descended from survivors of the Shoah, many more of us know that if grandparents or great-grandparents had not migrated here from Eastern Europe, our families might have perished in the catastrophe that was to come.

Indeed, modern British Jewry could be said to have originated as a refugee community, for the first settlers were descendants of exiles from Spain and Portugal who had been uprooted by religious fanaticism. Even after the Second World War, Jewish refugees continued to find a home in Britain, escaping danger in North Africa and the Middle East.

A few months before his death in 1996, the Reform leader Rabbi Hugo Gryn - who had arrived 50 years earlier as a teenager after enduring Auschwitz - said at a meeting to protest against restrictions on asylum-seekers: "Were it not for the liberal and welcoming policy of this country, our own community would not be here today."

For Jews, memory is integral to survival. A sense of history strengthens our collective identity and ancient rituals recall past events. But it is more than that: memory also shapes morality and the call to remember is a biblical imperative.

It lies behind one of the most widely observed Jewish practices, the Pesach Seder, a time of family celebration and plentiful food and wine. But the two definitive foods are the most basic - bitter herbs and matzah, lechem oni, the bread of affliction, which are aids to remember the Exodus, as the Haggadah says, as if you experienced it yourself.

Repeatedly, remembrance of Egypt is cited by the Torah as essential to remind the Israelites of their obligation to others, in particular to the stranger in their midst. Forgetfulnesss leads to callous indifference. In the JC earlier this year, Rabbi Baroness Neuberger, the daughter of a refugee from Nazi Germany, said that Pesach was about knowing "the heart of the stranger. And we can only do that by helping, and befriending, people less fortunate than ourselves. For me, that's the message of Pesach, and also the message of Judaism."

In the Guardian last week, Lord Sacks said that he "used to think that the most important line in the Bible was 'Love your neighbour as yourself'. Then I realised that it is easy to love your neighbour because he or she is usually quite like yourself. What is hard is to love the stranger, one whose colour, culture or creed is different from yours. That is why the command, 'Love the stranger because you were once strangers', resonates so often throughout the Bible."

In last week's Torah portion, for example, the Israelites, nearing the end of their travails in the desert, are told of a ceremony they must perform when they are settled in the Promised Land. Every farmer is to bring a basket of first fruits to the priests in an offering of thanksgiving.

The gift is to be accompanied by a set formula, which opens "My father was a wandering Aramean and he went down into Egypt" - a line that may sound familiar because it is included in the Passover Haggadah. At the moment they rejoice in the prosperity of a land flowing with milk and honey, the Israelites are commanded to remember their past.

Once the ceremony is concluded, the householders are urged to enjoy the produce of the land - together with those whom they are obligated to share it, including "the stranger in your midst".

In the previous week's Torah portion, a catalogue of commandments spelling out duties to the poor and vulnerable concludes, "You shall remember that you were a bondman in the land of Egypt."

Even more striking is another piece of legislation in the same portion. It is forbidden to return an escaped slave back to his master. If we extend the principle, refugees ought not to be returned to their place of persecution.

The same portion also contains a prohibition against Ammonites and Moabites ever entering "the assembly of the Lord". One of the reasons for their exclusion, the Bible states, is that when the Israelites fled Egypt, the Moabites and Ammonites showed no compassion to the refugees and "met you not with bread and water on the way".

Today, the duty to help refugees is recognised as a worldwide obligation. The right to asylum is enshrined in the Universal Declaration of Human Rights, drawn up in the aftermath of the Second World War. One of its architects was the French Jewish jurist and Nobel peace laureate René Cassin (whose name is borne now by a Jewish human rights organisation).

From that global perspective, Jews now have no greater responsibility towards refugees than any other citizen. But still Judaism calls on us to try to live up to its ideals.

Canvas huts will spring up across gardens for the festival of Succot later this month. A reminder of the flimsy booths dwelt in by the Israelites during the wilderness years, the succah has become a kind of paradox. Immigrant Jews in over-crowded tenement blocks had little room for one. Garden tabernacles, built from ready-to-assemble kits, signal the suburban comfort of their heirs.

But the succah is pre-eminently a symbol of impermanence and insecurity, the temporary home of a people on the run. Those who eat and even sleep in the succah may get to feel the autumn chill and drizzle - at least in north-west Europe - but they can soon return to the warmth indoors.Countless refugees in makeshift camps have no such option.

A group of young Jews from Britain have said they will be going to Calais to spend part of Succot building shelters in the refugee camps there. Translating memory into social action, they will take the message of the festival to the outside world and, in so doing, breathe new life into their ancestral tradition.