Fasting on Yom Kippur is one of the most popular of Jewish practices. Even among Jews who are distant from tradition, this is one mitzvah that the majority observes. Recent research indicated that 73% of Israeli Jews and 59% of American Jews fast on the Day of Atonement.

But why do we fast? Is it an endurance test? An act of self-flagellation?  A gesture of tribal identification? A fascinating Talmudic passage in tractate Yoma, 74b-75a suggests reasons for fasting on Yom Kippur that are both profound and little known. The Talmud shows a perspicuous understanding of the varied roles that food plays in our mental lives and what, precisely, it is that we disconnect from when we don’t eat for a day.

In a culture as food-obsessed as ours, where three fifths of Americans are overweight, and one fifth obese, this passage opens up new vistas of meaning in an ancient, revered practice.

The Talmudic discussion embarks from the verse in Leviticus 16:31, which states that on Yom Kippur, “you should afflict (or deprive) yourselves.” (v’anitem et nafshoteichem) Beyond sounding vaguely disagreeable, it is not obvious what the verse requires of us. The Talmudic rabbis make a series of attempts to decipher the biblical command and to deduce what it means in practice. Having considered and discarded several options (for example the possibility that it enjoins us to sit outside in unpleasant heat or cold,) the Talmud picks up the idea that the verse teaches us to deprive ourselves of food.

The Talmud bases this inference on Deuteronomy 8:3 which describes the Israelites forty year-long desert trek: “He afflicted (or deprived) you and made you hunger, and gave you Manna to eat.” For forty years, the Jews’ staple diet was Manna, a thin, whitish wafer-like substance which fell miraculously with the dew six days a week. The Torah uses the same Hebrew word inui, deprivation, both about fasting and about eating manna. Ergo, the Talmud concludes, the affliction of Yom Kippur includes deprivation from food.

The derivation is strikingly strange. For the Talmud is learning that we don’t eat on Yom Kippur from a verse telling us what the Jews did eat in the desert. What exactly is the comparison here? It seems that the affliction involved in eating Manna, was not the deprivation of nourishment per se; after all the people in the desert did eat. Rather, it involved other missing aspects of the eating experience. Two Talmudic rabbis argue about the nature of these absent dimensions:

“Rabbi Ami and Rabbi Assi discussed this: one said, “a person who has bread in his basket is not like one who does not have bread in his basket.” The other said: one who sees and eats is not like one who does not see and eat.”

The first of these statements suggests that the deprivation of eating Manna consisted of a kind of insecurity. The Torah teaches that the daily manna fall was calibrated to provide precisely what each person needed for that day and no more. If you attempted to gather more than your share, the excess would putrefy.  There was no certainty that manna would appear the next day either. One had simply to trust, whether in God’s faithfulness or the principle of induction, that tomorrow would be like today.

Maybe it was like the anxiety induced by an empty refrigerator. Who doesn’t know the dreary feeling of opening the fridge door to find an empty milk carton, left-overs from Saturday night’s Chinese takeout and a solitary yoghurt that’s about to pass its sell-by date? The manna was permanently just about to pass its sell-by date. It may have been delicious and nutritious, but the state of having just enough for today was, Rabbi Ami suggests, a kind of anxiety-inducing deprivation.

Rabbi Assi gives a different answer. He teaches that the deprivation of Manna is that it didn’t look like food. It tasted, the Talmud later tells us, like whatever you wanted it to taste of. But its appearance was plain and unappealing. Rav Assi suggests that the aesthetics of food, its colors, shapes, texture and mass are integral to a satisfying eating experience. Without that dimension, part of us goes hungry. (Think of slimmers’ magazines tips about how to make the food look pretty so you’ll eat less.)

A closer look at the Talmud’s biblical source from Deuteronomy 8 deepens our appreciation of the rabbis’ insight. As Levinas and others have taught us, when the Talmudic teachers cites biblical proof texts they are almost invariably concerned not merely with a narrow linguistic comparison, (in this case between two uses of the word “inui – deprivation)  but also with the wider context and resonance of the scriptural passage.

Our case is a striking example. Deuteronomy Chapter 8 has a fine, chiastic structure in which an evocation of the beauty and bounty of the Land of Israel is sandwiched between reminiscences of the austere desert wanderings when the people subsisted on Manna, in order to teach that “man does not live on bread alone, but on every word that comes from God’s mouth.” (8:3) After this schooling in simple living, the Torah promises that God will:

“bring you into a good land, a land with streams and springs and fountains issuing from plain and hill; a land of wheat and barley, of vines, figs and pomegranates, a land of olive trees and honey; a land where you may eat food without scarcity and you will lack nothing, a land whose rocks are iron and from whose hills you can mine copper.” (8:7-9)

These verses emphasize the cornucopia of food in the land and evokes it with sensuously vivid description. Moreover, the artful structure of the chapter in which the recollections of desert deprivation envelope the abundance of the Land of Israel, suggest that one is a preparation and protection for the other. Remaining mindful of the God-given sustenance of the desert can save us, amidst the abundance of the Land, from the easy illusion that “My own power and the might of my own hand have won this wealth for me.” (8:17)

In his understanding of the implied contrast between the experience of eating manna, and the promise of Israel Rabbi Ami picks up on the aspect of plenitude, highlighted in the verses, that was lacking from the desert eating experience. Rabbi Assi on the other hand emphasizes the visual and sensuous appeal of the produce of Israel, in contrast to the parev appearance of the manna. Both rabbis, though, affirm that the deprivation of fasting is not merely the cessation of nourishment, but also some other dimension of food that captures our desire and imagination.

But to what end? What is this temporary disconnection from food meant to achieve? The gemara’s continuation suggests an answer. The same Rabbi Ami and Rabbi Assi, share a series of reflections on what happens when desire and fantasy slip out of control, restraints break down; you start to view anyone else’s property as legitimately yours, says Rabbi Ami; you see all the forbidden sexual relationships as fair game, claims Rabbi Assi.

This series of observations ends with a pair of comments about the snake in the Eden who is cursed that “its bread shall be the dust.” Rabbi Ami interprets: “even if it eats all the delicacies of the world, they taste (to the snake) like dust;” Rabbi Assi says, “even if it eats all the delicacies in the world, it isn’t satisfied until it eats dust.”

How do these aphorisms relate to our two rabbis’ earlier observations? I suggest that they interpret the snake, emblem of untamed desire in Genesis, as an image of addiction. One who surrenders to an insatiable lust for the food, drink or substance that he craves is fated to a jaded state of sensuous degradation where everything tastes of that one thing or where only that one thing satisfies.

This reading is borne out by the following comment in the Talmud by Rabbi Yossi who wonders at the fact that, though the snake was cursed, yet he can find his favorite food, dust, wherever he slithers! What kind of a curse is that? It is the curse that the world inflicts on victims of addiction, whether the weakness is for food, alcohol, gambling or internet porn. The rich opportunities for others to profit from their enslavement ensure that wherever they look, they will find the object of their inflamed desire.

The plenty of the land and the sensuous beauty of its produce are good things, part of God’s promise and blessing. Yet these dimensions of our food may unhealthily consume us and colonize, or monopolize large tracts of our desire and imagination.

(Try a thought experiment: if you walk to work along an average mid-town Manhattan block, how many edible possibilities from how many cultures do you pass on your way to the office, and how much of your mental space throughout the morning is occupied with deciding which of them you will choose for lunch?) Remembering the desert and its lessons is a condition for remaining in the land and enjoying its blessings. One can have it all, if one also knows how to periodically step back.

On Yom Kippur, the Talmud is teaching, we withdraw from engagement in the world of eating, drinking and bodily pleasure. This offers a chance to release ourselves from the thoughts, fantasies and desires that can so preoccupy us and rebalance our relationship to eating.

We may then be free to direct desire towards our relationship with God, Who underlies all blessings.