Flowers, trees, and Torah

Flowers, trees, and Torah

Local scientist looks at Jewish texts with an ethnobotanist's eye

Dr. Jon Greenberg stands in the vineyard at HaGafen Cellars in California’s Napa Valley.

Okay. So why did civilization begin as a search for beer?

Who is the Jewish doctor who rescued tomatoes from witchcraft so we could have them on pizza?

Why did the apple, of all trees, become such a potent symbol of religion?

Well, to look for answers to those and many other surprising questions, look to ethnobotany, the subject that most interests Dr. Jon Greenberg of Teaneck.

When you know more about the plants the Torah mentions, you can have a more clear understanding of the metaphor and allusions that give life to the narrative. As is so often the case, the more you know, the more you can understand.

“Scientific knowledge can be useful as an aid to Torah learning,” Dr. Greenberg said. “It’s not biblical criticism, it’s not history per se – it’s really using the science to enrich our understanding and appreciation of Torah. That includes archeology, natural history,” and so much more.

Dr. Greenberg has a wide-ranging background. After graduating from Brown, he earned a doctorate in agronomy from Cornell, so his scientific credentials are impressive. He has researched corn, alfalfa, and soybeans for the U.S. Department of Agriculture and for the University of Pennsylvania’s Institute for Cancer Research, so he adds hands-on experience to his academic curriculum vitae. And he has religious credentials as well – he studied with Rabbi Chaim Brovender at Yeshivat Hamivtar in Israel. After having taught for many years on the university level, since 2008 he has been on the faculty of the Abraham Joshua Heschel School in Manhattan, and he regularly leads tours and offers programs that combine his twin loves – Torah and nature – in surprising ways.

For more information on two upcoming programs – where you can get the answers to the questions posed at the top of this story, because certainly we can’t give them to you here – take a look at the box that accompanies this story.

He teaches a course called Science and Torah, in which he and the students talk about the nature of science and the nature of Torah – “their agendas, the methods, and their assumptions. We look at a couple of areas where they interact, which includes creation and evolution. We look at six or seven different approaches to try to understand the relationship between those two things.

“We also look at other areas – for example, the question of scientific statements in the Torah. What do we do with them if they don’t correspond to our understanding? I look at different approaches. Some used the science of their day. When it gets to halachic issues, I saw that we can’t assume that the explanation given there is the ultimate reason. We really aren’t given reasons for them, so people have the tendency to explain them in terms that make sense for them. So if we don’t find it easy to accept a classical explanation for why we do a mitzvah, that doesn’t mean that we don’t have the obligation for the mitzvah any more. It just means that we don’t understand it.”

He used as an example the famous, once widely accepted belief that pork is not kosher because it can carry trichinosis. “These explanations can become dated very quickly,” he said.

The area that really piques his interest is that “often there is a deeper message being conveyed in the Talmud that is below the surface, beneath the literal meaning,” he said. He used as an example a story he has found himself citing frequently, he said. “Some people have the practice of adding a little olive oil when they open a container of olives, before they eat any. That’s based on two statements in the Talmud, about what was believed to help or to interfere with learning. One is that a person who eats olives often will forget his learning. The other is that a person who consumes olive oil often will retain things longer.”

This sounds odd. What can it mean?

“There are people who accept these practices, because rabbinical authorities tell them to, although now most people do not follow them. But whenever the Talmud takes an absolute statement like this one, we can rely on it being the case that the rabbis had access to much deeper sources of wisdom than we have. It is possible to get a much deeper lesson from this statement.

“Now I bring in agricultural and food history. Jews have been consuming olive oil since biblical times for cooking. But it seems that Jews only began to eat olives in Roman times. For anyone, eating olives was a new thing – it was the Romans who figured out how to cure olives to make them edible. There is no question about the olive oil being kosher; that rule is there to tell you that it is not enough to go by the letter of the law. You have to go by tradition, too.”

In other words, Dr. Greenberg said, “It is okay to enjoy the latest delicacy, but don’t do it constantly. Remember the real things in life. Don’t pursue trends. Keep your eye on the real purpose of life.”

His approach to the Talmud takes the commonly debated question of “how to understand it – do we take it at face value or look for deeper mystical and philosophical meanings?”- and turns it over. “I am using secular knowledge to reveal a deeper meaning,” he said.

Botanical metaphor is so deeply embedded in the prophetic literature that if we don’t understand the botany, we have a hard time getting the metaphor itself. “They don’t spell out what they’re talking about because it was obvious to everyone then,” Dr. Greenberg said. “If you lived close to agriculture and nature, you’d know. But now we have to reconstruct it.

“Psalm 128 has a very strange sort of blessing,” he continued. (“Your wife shall be as a fruitful vine, in the innermost parts of your house; your children like young olive saplings, round about your table,” it reads.)


“It’s not hard to explain the first half” – the wife as fruitful vine – “but the second part, about the olive saplings, doesn’t mean anything to us. But then every Jew had a few olive trees. Olive trees have two kinds of roots. The entire Mediterranean region has rocky, eroded soil. One set of roots grows deep into this soil, and can live for a long time. The second set of roots grows horizontally, just below the surface, and then turns upward and produces new shoots around the original tree. So olive trees are unusually long-lived; when a tree gets very old, the inside rots, but its own offspring have surrounded it like a windbreak. So the verse means that your children will support you when you are old; it’s a medical/social support system.

“Everyone then would have understood that intuitively,” Dr. Greenberg said. We need it explained painstakingly before we can get it.

But now, he continued, commercial agriculture has changed all that anyway. “We don’t want the old trees. We want small, young ones, packed in, so horticulturalists will remove the small shoots. We call them mamzorim” – bastards. “The meaning has changed because the agricultural practice has changed.”

Although Dr. Greenberg is not the first Torah-based ethnobiologist, he is one of very few, and he is forging new paths for himself. He is interested in working across the broad spectrum of the Jewish world, showing the relevance of the Torah to liberal Jews and the value of science to more traditional ones. He refuses any labels himself. “I try to stay off the spectrum,” he said. “‘Don’t divide yourselves into factions,’ the Rambam says. The Rambam considered it a part of the biblical commandment, and I take it as a way to avoid putting myself into any one faction.

“This is the best way to learn.”

Dr. Greenberg’s October schedule
Who: Dr. Jon Greenberg

What: Offers the Torah Flora walking tour of the Brooklyn Botanic Gardens and a program called “Noah’s Wine vs. Pharaoh’s Beer.”

The Walking Tour

Where: The Brooklyn Botanic Garden, 1000 Washington Avenue, Brooklyn

When: Sunday, October 12, at 10:30 a.m. and again at 2 p.m.

Why: To answer the questions posed at the top of this story, along with many others.

How much and directions: Details at Dr. Greenberg’s website,

For reservations: Email Dr. Greenberg at

“Noah’s Wine vs. Pharaoh’s Beer”

Where: The Jewish Center of Kew Gardens Hills, 71-25 Main Street, Flushing, N.Y.

When: Sunday, October 26, at 4 p.m.

Why: To explore why Pharaoh drank wine but Moses drank beer, what’s wrong with horseradish, and many other interesting ethnobotanical Jewish byways.

For whom: Everyone 18 and over; ID may be required.

How much: Free, but space is limited and reservations are required. Call (718) 263-6500.

For information: Go to

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