This is the sermon I delivered at Temple Sinai in Cranston, Rhode Island, on Yom Kippur 5786.

​In January of 2024, Temple Sinai gave me the chance to take a month-long sabbatical. I want to thank this holy congregation for giving me time for rest, renewal, study and travel. I also want to thank members of the Temple’s staff, lay leaders, and volunteers who stepped up during my absence. It was a reminder that this community is strong enough and active enough to take care of itself.

I spent the largest part of my time on sabbatical researching and writing about the history of the Jewish High Holy Days. I focussed on the way that the holidays have changed, particularly the changes in the way that Jews have understood the meaning of the holidays and their symbols. Today, I would like to share some of what I learned and wrote about.

The Torah says relatively little about Rosh Hashanah and Yom Kippur. Here is a key passage for both holidays:

“On the first day of the seventh month, you shall observe complete rest, a sacred occasion commemorated with loud blasts. You shall do no occupational labor and you shall bring an offering by fire to Adonai.… The tenth day of this month shall be the Day of Atonements. It shall be a sacred gathering for you. You shall practice self-denial and you shall bring an offering by fire to Adonai.” (Leviticus 23:24-27)

There are additional passages that describe the penalties for people who don’t observe the holidays. There is a description of the scapegoat ritual in which two goats were sacrificed to purge the Tabernacle and the people of their sin and impurity. But there are no details about prayers, confessions, or seeking forgiveness. There is no mention of rules for fasting, or what fasting means, apart from the cryptic phrase about “practicing self-denial.”

Most of what we actually do on Rosh Hashanah and Yom Kippur was developed long after the time of the Torah by the people we call “the rabbis,” the (mostly) men who wrote the Talmud and other central Jewish texts from about the 1st to the 6th centuries of the Common Era. The rabbis sought to transform the Torah – which was written in a time when most people were farmers and shepherds – into a way of living in partnership with God for their more urban and philosophical time.

The rabbis re-envisioned Rosh Hashanah and Yom Kippur into days for inward contemplation and transformation. They made the holidays into a ten-day period for making apologies for wrongdoing, asking for forgiveness, and feeling forgiven by God for a fresh start in the new year.

Rosh Hashanah and Yom Kippur did not stop evolving after the era of the rabbis. Through the medieval era and into modern times, the meaning and understanding of these days has shifted.  We are going to look at three different symbols of the holy days to understand that shift.

The Shofar
The first and most obvious symbol of the High Holy Days is the shofar, which we heard sounded last Tuesday and Wednesday on Rosh Hashanah. We won’t hear it again until this evening to mark the end of Yom Kippur.

The shofar was a basic musical instrument in the ancient world. The ram’s horn was used to muster the community when there was a natural disaster, a fire, or an attack from an enemy. It was used to signal troops in warfare to advance or retreat. It was also used in public rituals to mark the entrance of a king or the start of a public celebration.

It was natural for the rabbis to continue to use the shofar on Rosh Hashanah as described in the Torah. However, instead of using it to celebrate the beginning of the year, the coming of the fall harvest, or the entrance of a king, the shofar became a symbol for the sovereignty of God over our lives. The rabbis reimagined Rosh Hashanah as an annual coronation of God and the anniversary of God’s creation of the world.

We see this in the three sections of the Rosh Hashanah shofar service devised by the rabbis. The first section, Malchuyot (Kingship), acknowledges God as ruler of the world. The second, Zichronot (Remembrance), focuses on God’s covenant with the Jewish people. The third, Shofarot (Shofars), speaks of the shofar blasts heard at Mount Sinai and those that will be heard to announce the redemption of the world.

In medieval times, the shofar was again reimagined. The great medieval philosopher Rabbi Moses ben Maimon, known as Maimonides, described the shofar as a kind of spiritual alarm clock. He wrote that we should hear the shofar as an announcement saying, “Awake you sleepers from your sleep! You who slumber, arise! Inspect your deeds, repent, remember your Creator… Look to your souls! Improve your ways and your deeds and abandon your evil ways and thoughts.” (Hilchot Teshuvah 3:4)

Over time, the shofar has evolved from a battle cry and a trumpet fanfare, into a reminder of God’s rule over the world and of the covenant between God and the Jewish people, and then into a spiritual wake-up call to prod us to introspection. What will it be next?

Contemporary Jewish writers often remark on how the shofar is a complex symbol, making sounds that remind us of laughter, crying, and of alarm. We are in the midst of a time in which we are reimagining the shofar’s calls as a way to see God’s presence in all of life’s joys and sorrows.

The Book of Life
The second symbol of the High Holy Days I want to talk about is a symbol that is not a real-world object like the shofar. Rather, it is the imaginary book that looms large over this ten-day period: The Book of Life.

We refer to the Book of Life repeatedly in the prayer books of Rosh Hashanah and Yom Kippur. We even refer to it in the formal greeting for the High Holy Days, L’shanah tovah tikateivu v’techateimu, “My you be written and sealed for a good year,” and G’mar chatimah tovah, “May you have a good final sealing.”

In the book of Psalms, there is a verse in which the author talks to God about his enemies: “Let them have no share of Your goodness. May they be erased from the book of life and not inscribed among the righteous” (Psalm 69:29). This is probably the oldest reference to a “book of life” in the Hebrew Bible. It reflects an idea that existed for more than a thousand years in other cultures in the Ancient Near East – the idea of a divine book in which human affairs are recorded.

The difference between the “Book of Life” in the Hebrew Bible and what we see in other ancient cultures, though, is an emphasis on moral judgment. The author of the psalm says that God can change what is written in the book, and even erase it, according to whether people live up to God’s moral standards. In other ancient cultures, the gods’ record books were to assign each person’s fate – how many years each person would live, for example – a fate that could not be altered, not even by the gods.

This idea of the Book of Life was developed further by the rabbis, and they connected it tightly to Rosh Hashanah and Yom Kippur. In the Talmud, Rabbi Yochanan is credited with saying: “Three books are opened on Rosh Hashanah. One for the entirely wicked, one for the entirely righteous, and one for the in-between. The entirely righteous are immediately written and sealed for life. The entirely wicked are immediately written and sealed for death. Judgment for the in-between is left suspended from Rosh Hashanah until Yom Kippur. If they merit, they are written for life. If they do not merit, they are written for death.” (B. Rosh Hashanah 16b).

Notice that the description of three books is mostly rhetorical. I don’t think that Rabbi Yochanan believed that anyone is entirely righteous or entirely wicked. At the very least, he knew that those first two books would be extremely thin. His point is that everyone (no matter how good or bad they are) is given a chance prove themselves worthy – especially in the days between Rosh Hashanah and Yom Kippur. It’s the third book, and our ability to improve ourselves to get our names into it, that really matters.

The most famous Jewish text about the Book of Life is the one that we recited earlier this morning. The poem, Unetaneh Tokef, was likely written in the early medieval period. It conveys powerful images of God deciding “who shall live and who shall die … who by fire and who by water,” and so on. But you might notice that the poem makes some subtle and important changes to Book of Life of Rabbi Yochanan in the Talmud.

For one thing, there is only one book. Unetaneh Tokef makes no pretense that anyone is entirely good or bad. Also the poem states that it is not God who records judgments in the book. We ourselves are the authors of the Book of Life. The poem says that God only opens the book and “it reads from itself… each person’s signature is in it.” Through our actions, says the poem, we ourselves determine our fate.

There is one more thing I find powerful about Unetaneh Tokef. The most famous part of the poem – the list of ways that people will die – starts with a rather gruesome list: by the sword, by wild beasts, by starvation, and so on. But the tone shifts halfway through. The poem then asks, “Who will rest and who will wander? Who shall be at peace and who will be pursued? Who serene and who tormented?”

The poem wants us to consider that our real fate is not a matter of God’s decree about our moral righteousness. It is more a matter of our attitude. Whether you experience life as peaceful or tormenting, serene or restless, is as much about your outlook and the way you choose to accept life’s quirks and challenges.

So, we see that this central symbol of the Days of Awe, the Book of Life, has itself lived several different lives. It has gone from a heavenly score card that tracks human behavior, to a statement that we live in a moral universe in which our actions (good or bad) matter and have consequences, and then to a reflection on what makes a life truly fulfilling.

What should the Tree of Life mean to us today and in the future? It may be to focus on how the spiritual quality of our lives is determined by our choices. A life dominated by greed and anger may not be shorter than a life dominated by generosity and compassion, but it is likely to be more bitter, more fearful, and less joyful. A life dominated by service and kindness may not be longer or more luxurious than a life dominated by egotism and selfishness, but it is more likely to be hopeful and filled with love. We write ourselves into and out of the Book of Meaning and the Book of Joy and Satisfaction with every choice we make in life.

The Fast
The last symbol of the High Holy Days I’d like to discuss is one that might be on your mind right now as we move toward the afternoon of Yom Kippur, and that is the fast that many of us are experiencing right now.

Like the other symbols I’ve discussed, the fast of Yom Kippur is rooted in a passage from the Torah. In fact, it’s a verse I’ve already mentioned, the one that says, “You shall practice self-denial.” That phrase appears six times in the Torah, all of them in relationship to Yom Kippur. The confounding thing is, though, that the Torah never directly states what it means to “practice self-denial.”

Our best clue comes from the passage in the book of Isaiah that we read as today’s haftarah portion. The prophet says that the people complained to God by saying, “Why, when we fasted, did You not see? When we practiced self-denial, did You pay no heed?” (The verse equates fasting with the same phrase, translated as "practice self-denial," that we saw in the Torah.) God, in response, says that fasting does not earn divine favor when it is hypocritical – when, at the same time that people fast, they also allow the hungry to go without food and the unhoused go without shelter.

But why fast? What does fasting on Yom Kippur symbolize? How is going without food supposed to help a person seek and receive forgiveness?

The Talmud says that fasting is a form of personal sacrifice like the animal sacrifices that were conducted at the ancient Temple. Rav Sheshet asks God to accept the fat and blood he loses during the fast as if it were a ritual sacrifice offered on the altar to atone for his sins. (B. Berachot 17a).

I don’t know about you, but I find this interpretation difficult, unsatisfying, and even a bit grotesque. I definitely don’t think of the pound or two I lose on Yom Kippur as any kind of animal sacrifice. Even if I did, it would just make me feel even more guilty about the three or four pounds I am bound to put on during the break-fast after the end of Yom Kippur.

By the medieval era, the purpose of fasting had become more cerebral. In the 12th century, Maimonides wrote that the fast was to elevate the soul. By releasing us from worldly distractions, the fast would help us separate ourselves from material distractions so that our focus on Yom Kippur could be solely on the spiritual pursuit of repentance.

In the 20th century, Rabbi Abraham Joshua Heschel, had a very different take on fasting. Heschel connected the fast directly to the prophecy of Isaiah that chastises people for fasting while, at the same time, oppressing the poor. Heschel wrote that the fast challenges us to put our beliefs into practice. Fasting should help us feel solidarity with the poor and all who are deprived of basic needs. The ritual of fasting, he said, is only meaningful if it awakens an urgency to address the suffering of others.

The Yom Kippur fast began as an act of mortification in which people would afflict themselves with hunger to cleanse away their sins. The rabbis, mourning the loss of the Temple, turned it into a substitute for animal sacrifices to earn God’s favor and forgiveness. In the medieval period, it became a meditative practice to subdue the desires of the body in favor of the spirit. In the modern era, it has been likened to a call-to-action to prod us toward pursuing social justice.

What should it mean to us now? How should we make fasting on Yom Kippur a meaningful practice for today?

Here’s another take. Yom Kippur is a day of taking ourselves to the edge of our ego. On this day, we try to come to terms with the mistakes we make in life repeatedly – the bad habits that we just cannot seem to get rid of.

We all have habits we know that we would be happier without: an anxious need to keep up a break-neck speed in our work, reluctance to turn off the electronic gizmos, repeated failure to confront the way we hurt people who are close to us or to see the pain we have caused. It is so hard to change, even when we know that change would make us happier. Our egos convince us that we don’t have to change. Part of us keeps saying, “I know that what I’m doing is wrong, but I have to do it anyway. I’m too set in my ways.”

That’s where the fasting comes in. On Yom Kippur, we spend an entire day doing whatever it takes to break down that ego. We repeat prayers that remind us of choices that are not working – for us or for anyone else. We deprive our bodies of food to confront our mortality and to remember how fragile and short our lives are. Fasting on Yom Kippur leaves us naked of our conceits and our belief that we are the center of the universe.

We hope to reach the point where our defenses will be exhausted. A full day of fasting and asking for forgiveness helps us to see the foolishness of clinging to old habits. The fast helps us give in to the reality that we are imperfect. It helps us realize that we can and should do better … that we can and should be happier.

Will today be the day that you break down your ego and allow yourself to change to be a better person – maybe even a happier person? Why shouldn’t it be today?

Looking at the Past to Understand the Present and Future
We look at the Jewish past to see how our understanding of our practices have changed because we, too, are a part of Jewish history. As much as the rabbis of the Talmud, the medieval philosophers, and modern commentators, we here at Temple Sinai are helping to shape the Jewish future and the way that Jews make our tradition meaningful for ourselves and for future generations. By examining past understandings and our own understanding of our tradition, we help keep it alive as an inspiration and a source of meaning for today’s Jews – not as an object to be viewed as if it were an exhibit in a museum.

Yom Kippur is meant to be a day that challenges us to be better people, and that idea is timeless. It is our obligation to find the symbols, rituals, metaphors, and interpretations that make this day a day that can change our lives.

The research and writing I did on the history and meaning of the High Holy Days during my sabbatical in 2024 has had an impact on the way I think about these holidays, both as a rabbi and in my own personal spiritual life. I will always be grateful to this congregation for giving me the time for this learning and reflection.

I will be taking another month-long sabbatical in the summer of 2026, during which I will continue this work. It hope that it will inform the way that I lead our High Holy Day services and it will inform the way that I care for myself and my family.

Again, thank you for giving me the time to do this. And thank you for your own commitment to hearing the shofar, writing your name in the Book of Life, and of pushing yourself to be better and to be happier. May Yom Kippur be meaningful for you this year – and year after year.

G’mar chatimah tovah,
May you be sealed for a good year.

This is the sermon I delivered at Temple Sinai in Cranston, Rhode Island, at the Kol Nidre service on October 1, 2025.

​My family and I vacationed in the San Francisco Bay Area last year. On the second-to-last day of our trip, we spent an afternoon at Muir Woods National Monument just north of San Francisco. The park has some of the most famous old growth coast redwood trees in the world. The trees there plant their roots in the water of Redwood Creek and they soar above the foggy marsh to heights of 250 feet and more. The trees are breathtaking. They are even more astonishing when you consider that these trees began life, 500 to 1,200 years ago, as seeds no larger than an eighth of an inch.

As I admired those redwood trees, the question occurred to me, where did they come from? I don’t mean in a spiritual or figurative sense, but a very literal and material one. Some of the older coast redwood trees in Muir Woods weigh more than a million pounds. That’s not an exaggeration – one million pounds. All that mass had to come from somewhere. Where did all of that material come from?

Now, people have this idea about trees. We say, “trees grow out of the ground,” and that seems to make sense. We see that they have big roots burrowing down into the earth, so we imagine that this is where they get their substance – drawing it out of the ground through their roots. 

But this is not actually how trees work. That becomes clear when you consider that there is no big empty hole beneath a tree from which it drew its material. If a million pounds of redwood were sucked out of the ground, there would have to be a huge void left behind.

A 17th century scientist from Brussels named Jan Baptist van Helmont discovered this when he conducted a simple experiment. Van Helmont grew a willow tree and he measured the weight of the soil it grew in, the weight of the tree itself, and the weight of the water he added to it. After five years, the tree had gained 164 pounds, but the weight of the soil was nearly the same as it had been when he started the experiment. From this he concluded that the tree’s weight did not come from the ground, but that it came entirely from water. 

He was right that the tree does not consume the ground. But he was wrong about the water. Trees do not build their weight from water. So, if it’s not from the soil and it’s not from the water, where does a tree’s mass come from?

You might be thinking about the biology class you took in ninth or tenth grade and remember that there’s a process called photosynthesis that requires sunlight. Trees and all green plants need sunlight to grow. So, does the tree’s mass come from sunlight? Do trees directly convert energy into mass? No. Wrong again.

Let’s go back to that high school biology class and the process of photosynthesis. Green plants take in carbon dioxide from the atmosphere and water from the soil. They use the energy in sunlight to strip the carbon atom off of carbon dioxide (CO2) and recombine it with the oxygen and hydrogen from water (H2O) to turn into a sugar called glucose – (C6H12O6, for anyone who’s taking notes). That glucose becomes the building block for almost all of the plant’s mass – leaf, branch, stem and root. The plant also releases some oxygen back into the atmosphere as a helpful byproduct of this process. 

When I say “helpful byproduct,” I mean “helpful” as in, “allows all animals on this planet to breathe.” That kind of helpful. It is also “helpful” in the sense that, by removing all of that carbon from the atmosphere, plants transform the earth into a place where all kinds of life can thrive and not a scorching hot rock with temperatures magnified by the greenhouse effect. 

If you haven’t thanked a plant lately, now might be a good time.

The upshot of all of this is that the source of most of a tree’s mass – 95 percent of it – comes from the heaviest element that it takes in – carbon. And where does all of that carbon come from? You’re breathing it right now. It comes from the carbon dioxide, CO2, in the air. Plants turn air into solid material. The tens of thousands or hundreds of thousands of pounds in a tree – a million pounds in a large redwood – come from the carbon dioxide in the atmosphere. Trees are literally made out of thin air.

Now, I’m going to come back to those real, literal trees in a little while, but first I want to use trees as the foundation of a metaphor. There is a long tradition of trees being used as symbols in Judaism. In the book of Proverbs, the Torah is called “a tree of life to those who hold fast to it” (Proverbs 3:18). And the menorah – the seven-branched candelabra you see on either side of our ark behind me, the oldest symbol of Judaism – is actually modeled on the branches of a tree. You might also remember the burning bush – a small tree – from which God spoke to Moses. For thousands of years, Judaism has used trees as a symbol of life and of God’s presence.

Just as it is literally true – against all of our intuition – that trees grow out of the air, we can figuratively say that our lives are also made out of things as insubstantial as thin air. Think about it. What are the things you most value in your life, the things that give you a sense of meaning and purpose? Chances are, the first things you think of are not your house, your car, and your bank account. You probably have an intuitive sense that the real foundation of your life is in other things: friendship, trust, compassion, justice, faith, belief, and love. 

In this sense, we are similar to the trees. We may look substantial and other people may see us first for our physical and material assets, but our lives are truly composed of things that are not things at all. Our existence is built out of thin air (metaphorically speaking).

What would your life be without the relationships you value the most? What would it be without your values and beliefs, hopes and aspirations? Most people would agree that life would be miserable and meaningless if life were just about our possessions and physical attributes. When the pursuit of the material becomes the central focus of a person’s life, it magnifies unhealthy attitudes: envy, greed, hardheartedness, and a belief that no amount of wealth can ever be enough.

When healthy, our lives are built upon values that cannot be weighed on a scale and that cannot be perceived under any microscope. Our lives are the cumulative assemblage of dreams, thoughts, emotions and wisps of hope.

Jewish tradition strongly endorses the idea that it is the non-material that really matters in our lives, and it warns us against worshipping “stuff” – things that can be seen, bought and sold. This is the essence of the second of the Ten Commandments – “You shall have no other gods besides Me. You shall not make for yourself a sculptured image, or any likeness of what is in the heavens above, or on the earth below, or in the waters under the earth.” (Exodus 20:3-4).

You thought that the second commandment was just about not worshipping idols? It means much more. 

The second commandment is interpreted in Jewish tradition to mean that we should be on guard against the human tendency to think that our lives are based on things that are dug out of the ground, built by our hands, parked in our driveway, or saved in a bank. Our reverence should be reserved only for the God that cannot be represented in any physical form because God represents values that have no material substance.

The things that we should really revere in life are the divine attributes we experience in our most precious moments – the lift we feel in our soul as we watch our children grow up, the satisfaction and joy we experience when we help a friend in a difficult moment, the integrity we feel when we right a wrong, and the warmth in our soul when we embrace our beloved. That is what makes up the substance of our lives – and it comes to us as if out of the thin air.

And now, I want to come back to those very real and literal trees. As I said, one of the ingredients that allows trees to turn air into solid wood is sunshine. The energy that is absorbed by a tree’s leaves from the sun is used in the process of photosynthesis to turn carbon dioxide into glucose. The energy of that sunshine does not just disappear as the tree grows, or even after the tree dies. The energy is stored in the chemical bonds in every molecule of the tree. 

As you surely know, if you add enough heat to a tree it will start a chain reaction that can toast your marshmallows…or burn down a forest. Human beings have used the stored energy in trees for hundreds of thousands of years – either as firewood or as coal. It was our main source of energy until the development of petroleum in the 19th century. 

It is only in recent centuries, though, that we have used so much of the world’s trees that we face a worldwide crisis. In the last 300 years, roughly 35 percent of the earth’s forests have been lost to agriculture, urbanization, and logging. About half of those losses have occurred in just the last century. As we destroy our trees, we also damage the earth’s ability to remove carbon dioxide from the atmosphere to make the world habitable for human beings.

We can now return to the metaphor in which we recognize that our lives are sustained by ideas and values that are as insubstantial as the air from which trees derive their mass. Those ideas and values can also be burned to the ground. If we are particularly poor stewards of our lives, we can destroy the ideals and beliefs that sustain us. They are as inflammable as dried leaves. It is a painfully easy mistake to make.

When people lose sight of what really matters, and put their trust instead into wealth, status, fame or ego, they are metaphorically burning down their own house. Relationships are lost, values are sacrificed, and paranoia blossoms. I’m sure that you have seen this happen to people as I have seen it happen. Just like a tree, our lives can be destroyed by the fires of thoughtless greed, egotism, and tyranny. 

This is also true of the values and beliefs that we share as a society. Justice only exists so long as people hold its rules and customs as sacred. When a system of justice is treated as a game to wield power over others or to punish enemies, it loses its meaning and part of the glue that holds society together is lost. 

Equality only exists as long as people agree that every life is sacred and everyone deserves to be treated with dignity and respect. When we give in to the impulse to treat some as superior and others as inferior, we burn down the promise that all lives matter.

Hope – that word on the Rhode Island state flag and the word that is the translation of Israel’s national anthem – is made out of people’s shared ability to believe that things can be better than they are. Without hope, we lose the energy to repair what is broken in our lives and in our world. Without hope, we lose the ability to believe that our aspirations have any chance of ever being realized.

Justice, equality, hope, faith, integrity, and many other foundational values, too, will not be found as a literal ingredients in the bricks that build our homes, in the fuel that fills our gas tanks, or the food we put on the table. We might be tempted at times to say that we can’t live off of these insubstantial, high-minded ideals. In a real sense, though, they may be more important to living a meaningful life and to building a sustainable society than concrete, steel, oil or wheat. We, like the trees, are sustained by the insubstantial and our lives are built out of thin air.

On this Yom Kippur, take a look at your life and ask yourself what are the true foundations of your life. Consider the loving relationships that give you a real sense of meaning and fulfillment in life. If you are not paying enough attention to some of them, decide today to begin feeding them as they require and deserve. Think about your beliefs and values and pick out the three or four that really define who you are as a person. Recommit yourself to putting them at the center of your decisions and life choices. Make a list of the principles that you hold dear as the basis of a society you would like to live in. If you feel that they are fading, stand up to proclaim what you stand for.

All of these ideas, beliefs, relationships and experiences are fragile. Consider how easily they could disappear like smoke unless we make the conscious choice to tend and nurture them. Remember that our lives are not as permanent and fixed as we like to think they are. Our existence stands on a foundation of air. 

On this Yom Kippur, let us remember the things that really matter to us that are not things at all. Let us dedicate ourselves to a year in which we place our highest values and dearest beliefs at the front of our lives, so that we will know that they are a tree of life when we hold fast to them.

G’mar chatimah tovah.
May you be sealed for a good year.