THE Jewish comedian Jackie Mason likes to tell audiences what's special about his co-religionists: at night, he explains, when theatres disgorge their audiences, and most people ask their friends, "Would you like to go for a drink?", Jewish theatre-goers are the ones asking instead, "Have you eaten?"

It is no secret that food is important to Jews. This goes beyond cultural stereotypes: the crucial role of food is woven into the very fabric of the Jewish religion. Each time we eat, the Torah teaches, we make a choice: whether to use this opportunity to elevate ourselves, or to become degraded. With each meal, we have the chance once again to decide whether to allow G-d to dwell in greater measure in this world, or - G-d forbid - the opposite.

To understand how food gives us such power, it helps to look first at how Judaism views holiness. Rather than existing in a specific location or time, Judaism teaches that holiness can infuse our every action, our every moment, if only we learn how to use our seemingly mundane activities to channel these divine sparks.

The great Rabbi Menachem Mendel (1787-1859) - the "Kostker Rebbe" - was once asked by one of his students, "Where can G-d be found?" As the rebbe prepared to answer, his other students gathered round. One was certain the rabbi would answer that G-d can be found in heaven. Others were sure the rabbi would say that G-d could be found in the synagogue, or the study hall; perhaps in the homes of the very pious . . .

Finally, the Kostker Rebbe cleared his throat and declared: "G-d can be found wherever we let Him in."

EATING - the act of sacrificing another life, whether plant or animal, for our own - is especially fraught with meaning: through this act, we can choose to be animalistic and callous, or, if we choose, we can use it instead to transcend our animal nature. The laws of keeping kosher, or kashrus, give us a key: a unique opportunity to use our actions for good, as a way of channelling holiness into our everyday lives.

Much of the Torah is concerned with instructions on how to treat animals without cruelty. We mustn't yoke a stronger animal with a weaker one (Deuteronomy 22.10); we're commanded to chase away a mother bird before taking her eggs (Deuteronomy 22.6-7); we're not to muzzle an ox while it is treading out corn (Deuteronomy 25.4). The Talmud goes further, instructing that we feed our animals before satisfying ourselves (Berachot 40a).

When it comes to viewing animals as food, kashrus also tries to minimise suffering. We're forbidden to boil a calf in the milk of its own mother (Deuteronomy 14.21); animals cannot be slaughtered in view of others. Only specially trained rabbis can kill a kosher animal: they are forbidden from being paid by the animal, lest they are tempted to rush; and kosher slaughter is performed as humanely as possible, by severing the ceratoid artery with a knife that is sharpened between each slaughter.

These rules are important in maintaining humane conditions for animals. But the safeguards of kashrus are designed not only for animals, but for us, to instil in us an extra sensitivity to the feelings of others.

Take the biblical injunction not to cook a kid in its mother's milk: it is needlessly cruel, the Rabbis maintain, to make the source of an animal's nourishment an instrument of its death. Though this commandment does safeguard animals, its real object is to teach us to feel for everyone; to consider the feelings of others, from the most exalted to the lowly - even to the animals that we eat.

The prohibition against boiling a kid in its mother's milk was actually expanded by the rabbis, who forbade all milk and meat products from ever mixing. Kosher-keeping Jews thus today eat either "meat" meals containing no dairy products, or "dairy" meals containing no meat; even kosher restaurants are designated as "meat" or "dairy". In this way, with every meal - with each bite - kashrus reminds us to see the big picture: to remember that our actions have consequences, and that, each time we act, we can choose to be heedless, or to be kind.

Kashrus reminds us that we each live in two worlds: the physical and the spiritual. Rather than try to banish our physical urges, Judaism urges us to exalt them instead: to put our basest desires to holy ends. Kashrus gives us a beautiful vehicle for this, allowing us to turn the physical act of eating into a manifestation of G-d's will and kindness.

Yvette Alt Miller is the author of Angels at the Table: A practical guide to celebrating Shabbat.