As if mocking the scenes of jubilation at London's successful 2012 Olympics bid, the terrorist explosions that came the next day left devastation in their wake.
In all our synagogues, British Jews are joining our prayers with those of others, grieving for the dead, praying for the injured and sharing our tears with those of the bereaved (see story, page 14).
Terror has become the scourge of our age, and it will take all our inner strength to cope with it. I have met far too many victims of terror: survivors of the Istanbul synagogue bombing in 2003 and the 1994 terrorist attack on the Jewish community center in Buenos Aires; in Israel, where almost everyone knows someone who has been affected, as well as survivors of the massacres in Cambodia, Bosnia, Rwanda and Kosovo.
Like others, I have wept for the broken families and shattered lives and the injuries, physical and psychological, that may never heal.
But I have wept also at the courage of the victims. Each year, I go with a group to perform concerts for people who have suffered terrorist attacks. One we met was an 11-year-old boy who had lost his mother, father and three other members of his family in a suicide bombing. He himself had lost his sight.
In the hospital ward, the boy sang with the choir a hauntingly beautiful religious song. We had gone to give him strength; instead, he gave us strength.
Terror fails and will always fail, because it arouses in us a profound instinct for life. Will we ever forget the heroism of the New York firefighters on Sept. 11, or the courage of the passengers on United Airlines Flight 93 or the kindness of strangers who brought comfort to the traumatized survivors?
Terror makes us vigilant in defense of what we otherwise take for granted: the sanctity of life, the importance of freedom and the countless natural restraints that allow us to live together in safety and trust.
Free societies are always stronger than their enemies take them to be. Enemies of the West mistake its openness for vulnerability, its tolerance for decadence, its respect for differences for a lack of moral conviction.
Britain has exceptionally strong links of friendship among its different faiths and ethnic communities. That is a vital source of stability when nerves are frayed and fears aroused. London itself has a long history of courage. That, too, was evident in the calm that prevailed on July 7.
The best response to terror is not anger, but the quiet strength to carry on, not giving way to fear. I think of Judea Pearl, father of murdered Wall Street Journal reporter Daniel Pearl, who has become a campaigner for deeper understanding between Islam and the West. When I asked him what motivated him, he replied, "Hate killed my son, and you cannot defeat hate by hate."
I think of one of the most promising young men our community has produced, 19-year-old Yoni Jesner, who was killed in a Tel Aviv suicide bombing. His family, out of deep religious conviction, donated his organs to save lives -- among them a 7-year-old Palestinian girl who had waited two years for a kidney transplant.
Michael Walzer, a leading American political theorist, has written, "Terrorists are like killers on a rampage, except that their rampage is not just expressive of rage or madness; the rage is purposeful and programmatic."
Its victims, deliberately, are the innocent and the uninvolved: workers in an office, passengers on a train, passersby on a pavement. Its aim is fear. It advances no interest. It has no conceivable claim to justice. It dishonors any cause it claims to represent.
The real answer to terror was enacted in London and elsewhere five days before. Millions of people took to the streets and parks to demonstrate their solidarity with the victims of poverty in Africa. Their methods were peaceful, their weapons were song and celebration, and their greatest strength was the justice of their cause.
The people with whom they were identifying -- the hundreds of millions of children who lack food, shelter, clean water and medical facilities, sustenance and hope -- have never resorted to terror to bring their plight to the attention of the world, nor did they need to.
The choice humanity faces was set out long ago by Moses: "I have set before you life and death, the blessing and the curse. Therefore choose life, so that you and your children may live."
The strongest answer to the forces of death is a renewed commitment to the sanctity of life.
This column first ran in the Times of London on July 9, 2005.
Sir Jonathan Sacks is Orthodox chief rabbi of the United Kingdom and the British Commonwealth and associate president of the Conference of European Rabbis.