Terror has come to the streets, the trains and the buses of London. And we, who have grieved so often for attacks on our people in Israel, Buenos Aires, Paris, Marseilles, Istanbul, Djerba and Mombasa feel in our bones the shock and grief, the fear and trauma of those affected.

We know what it is to phone the members of our family, one by one, to check that they are safe. We know, from the experience of Israel, what it is to find simple acts we once took for granted - a bus ride, a meal at a restaurant, a shopping expedition, a journey to work - to become fraught with anxiety and insecurity.

And so we say from the depths of our heart that our thoughts and feelings are with the victims and their families. May Hashem bring them refuat hanefesh urefuat haguf, physical healing and psychological healing. May He help the police and security forces find the perpetrators and bring them to justice. And for all who plot evil against us and against the innocent, may He thwart their counsel and frustrate their plans, so that the people of the world may live in safety and tranquillity with none to make them afraid. Kein yehi ratzon venomar Amen.

It is no coincidence that this week we read the sedra of Chukkat. On the face of it, nothing could be less relevant to the problem of terror than the ritual of the parah adumah, Red Heifer. But it isn't so. To the contrary it is this week of all weeks that the Torah speaks about life and death and their relationship to religion and faith.

The Torah speaks about certain of the commands as chukkim, a word we normally translate as "statutes". These are the commands that many ages and many sages have found difficult to understand. They include such mitzvoth as the prohibition of eating milk and meat together, or of mixing wool and linen, or sowing a field with different kinds of crops. They are the commands that seem to have no reason, no logic. Rabban Yochanan ben Zakkai said about them: chukah chakakti ugezerah gazarti, ve-ein lecha reshut leharher achar middotai. "I have issued a decree, enacted a command, and you have no permission to doubt My rules and their purposes."

Of these, the supreme example is the parah adumah, the red heifer. As the Torah says: Zot chukkat ha-Torah. This is the statute of the Torah, the one that more than any other exemplifies the idea of a command whose reason is beyond our understanding.

Saadia Gaon held that chukkim were commands G-d gave us for the sake of obedience alone. Rambam ( Moses Maimonides) held that chukkim were commands intended to wean us away from idolatry. Ramban (Nachmanides) and R. Shimshon Raphael Hirsch believed that they were what today we would call ecological commands: rules that teach us to respect the integrity of nature.

But there can be no doubt that the mitzvah of parah adumah had to do with life and death. It relates to the supreme source of impurity in Jewish law - contact with or proximity to a dead body. A person who had become defiled had to be purified before he could enter holy space, the precincts of the Temple. The reason is that G-d is the G-d of life. As we say in our prayers at a funeral:

"In the way of righteousness there is life; along that path there is no death."

It is difficult for us to understand how radical an idea this was. Ancient religions were obsessed with death. The pyramids are giant mausoleums, burial places, monuments to death. Death was the realm of the spirits, the place where the soul was freed from the strife and struggle of the physical world.

We too believe in olam haba, life after death. But the emphasis in Judaism has always been on life in this world, not the next. As David Hamelekh said in a Psalm we say every day:

"What profit is there in my death if I go down into the pit? Can dust acknowledge you? Can it proclaim your truth?" We say in Hallel lo amut ki achyeh ve-asapper massei Kah. "I will not die but I will live to tell the works of G-d." At the heart of Judaism is a monumental, majestic celebration of life. We can now begin to understand the ritual of the red heifer and its significance, and not just that but the other chukkim as well.

Human beings have irrational impulses. They are, as scientists say, hardwired into our genes. Rambam, in the section of his law code called Hilkhot Deot, was one of the first to argue that certain of our characteristics are genetic in origin. And some of them are profoundly harmful. We have a natural tendency to fear and fight and commit acts of violence. That is what the Torah means when G-d says, after the Flood, "Never again will I curse the ground because of man, even though every inclination of his heart is evil from childhood ."

How do you combat irrational instincts? Not by rational commands. Reason all too often has no power against primitive urges and instinctual passions. The only way to fight instinct is by commands that say: Just don't do it. Don't rationalize. Don't engage in intellectual debate. Just don't do it. That is the meaning of the chukkim.

We know all too well in the 21st century just how great is the human capacity to destroy the natural environment. Wherever human beings have gone, they have destroyed animal and plant species. Easter Island was once full of trees and plants and animals and birds, until human beings came and within centuries destroyed them all. We are still, even today, creating ecological disaster. And so the Torah said: respect species. Understand that each has a part to play in the total environment. Don't tamper with them. Don't mix plant and animal life - linen and wool. Don't sow a field with mixed kinds. Don't confuse life and death - milk, the symbol of life, and meat, the symbol of death. Don't ask why. It takes centuries, many lifetimes, before one day human beings understand environmental catastrophe, and even then, that understanding does not always lead to action. Just obey the rules. That is a chok. A law we keep without always understanding why, but a law that is vitally necessary if life on earth is to survive.

Of all natural instincts, the worst is the human impulse to kill other human beings. Sigmund Freud called it thanatos, the death instinct, the impulse to destroy, which is sometimes so strong that we don't mind if we too are destroyed in the process. Freud believed that this was one of the two great instincts that shape human behaviour. Eros and thanatos: the instinct for life and the instinct for death. Both are strong. Both are irrational. And the question in any age is: which will prevail? More than three thousand years before Freud, Moshe Rabbenu asked the same question, posed the same choice:

"This day I call heaven and earth as witnesses against you that I have set before you life and death, the blessings and the curse. Therefore choose life, so that you and your children may live."

Now we begin to understand the parah adumah, the red heifer. In ancient pagan religions, the realm of the gods and the spirits was the realm of death. Death was sacred. Even in ancient Greece and Rome the highest honour was to die for your country. Against these cults of death, Judaism rose up in protest. Death isn't sacred. Life is sacred. G-d is the G-d of life. Judaism is the religion of life. Choose life.

The idea, in Judaism, that death defiles - that if you have had contact with a dead body you aren't allowed to enter the Temple - is the most powerful statement ever made that life is holy. Death doesn't bring you closer to G-d. Death separates you from G-d. What an idea! And how urgently we need it today! The law of the red heifer was a chok. Zot chukkat haTorah. It was a law that bypassed reason and spoke directly to instinct - because the death-impulse bypasses reason and speaks directly to instinct.

And what was the ritual of the red heifer? To take ashes of a red heifer - ashes that signify the death of something that was once very much alive - and dissolve them in mayim chayyim, "living waters", the waters of life. The ritual of the red heifer showed, graphically, instinctually, how life is stronger and more sacred than death.

We are living in an age of terror. The train and bus bombings this Thursday brought it suddenly close to all of us. What is terror? It makes no sense. It advances no cause; wins no sympathy; achieves no goal. It is destruction for the sake of destruction. It is the death instinct in our time.

What Freud saw in the 20th century, and what the Torah taught us 33 centuries ago, is that the death instinct is real and dangerous and must be fought at every level - above all at the religious level. We say today, as our ancestors have always said, death is not holy. Life is holy. Contact with death does not bring us close to G-d. It separates us from G-d. You cannot get to heaven by creating hell on earth. You cannot serve the G-d of life by worshipping the instinct for death. Terror is not just brutal, random, destructive; terror is not just evil; terror is the ultimate desecration.

Today we join our thoughts and prayers to those of the nation. We weep for the victims: for the dead, the injured, the bereaved. We weep for the fear that has now come to these shores. We weep for the mindless, meaningless destruction that brings death and fear where there should be life and trust.

And we say quite simply to the terrorists, their supporters and sympathizers: If you want to bring your cause to the attention of the world - look at what happened a week ago. Millions of people throughout the world took to the streets and parks in sympathy with the people of Africa, the poor, the hungry, the starving, the children who have no food, no clean water, no medical facilities, no hope. Did they, the real victims, need violence to bring their plight to the attention of the world? No. Did their supporters in Hyde Park and elsewhere need terror? The opposite. Their weapons were music and song and a celebration of life. A cause that needs terror is an unjust cause. A cause that uses terror is an unholy cause.

The choice humanity faces in the 21st century is the choice the Torah set before us long ago: "I have set before you life and death, the blessing and the curse. Therefore choose life, so that you and your children may live." May Hashem help us and all the people of the world to choose life, honour life, enhance life, sanctify life, bimhera beyamenu Amen.

© Copyright Office of the Chief Rabbi 2001 - all rights reserved. Reproduction of this Web site, in whole or in part, in any form or medium without express written permission from the Office of the Chief Rabbi is prohibited.