(An herbalist prophecy with room for science and tradition; February 2026)
At the bitter springs of Marah (Parshat BeShalach, Exodus 15:22-26), we see the people of Israel turn away from their dealings with the Egyptians and travel into the desert, where they begin to face the conflicts and challenges of independence. In the desert, they will rely on God as they learn to innovate and to govern and fend for themselves. They must constantly revisit the balance between faith and dependence on God, on the one hand, and their growing agency on the other. This national adolescence includes as much turbulence and as many setbacks as any teenager experiences.
The Torah’s account of the incident at Marah is terse, consisting of only five verses:
“Then Moses had Israel travel from the Reed Sea and they went out to the wilderness of Shur; they traveled three days in the wilderness and did not find water. They came to Marah, but they could not drink water from Marah because it was bitter; therefore it was called Marah. The people complained about Moses, saying, “What shall we drink?” So he cried out to the Lord, and the Lord told him about a tree [or wood]; he threw it into the water and the water became sweet; there He gave them an edict and a judgment; there he tested it.”
The last phrase, “there He gave them an edict and a judgment; there He tested it” has inspired many interpretations that are represented in the Midrashim and the writings of the commentators. Rabbeinu Bechaye ben Asher ibn Halawa (Zaragoza, Spain, 1255-1340) suggests an interesting approach. He interprets “an edict and a judgment” to mean that God provided Moses with two sources of knowledge about survival in the desert and the uses of the plants found there. The Hebrew “chok,” translated here as “edict,” is usually understood to refer to Biblical commandments such as the dietary laws for which no reason is given or implied by some social purpose. “Mishpatim,” translated literally as “judgments,” include laws such as the prohibitions of theft and murder that serve a practical social purpose and in many cases have similar counterparts in other cultures. Rabbeinu Bechaye describes two types of knowledge of herbalism. By analogy to the usual meanings of these words, he proposes that in this passage, “chok” refers to traditional or revealed knowledge, and “mishpatim” consists of empirically verified information that we might call scientific knowledge today.
The idea of empirical knowledge as part of a prophetic revelation may seem like a contradiction. In the context of the social transformation that began at Marah, it is complex and dynamic, but not contradictory. Rabbeinu Bechaye shows us how reason and experience can interact with revelation. Most of the commentators take the phrase “there he tested it” to mean that God tested the faith of the people of Israel with the challenge of lack of potable water. Rabbeinu Bechaye, in contrast, explains it as meaning that Moses tested the wood by throwing it into the water. He paints a remarkable picture in which Moses learns the ability of this wood to purify water in a Divine revelation, and then decides to check for himself whether this is really true! Here we see the challenge of the generation of the Exodus in a nutshell: Throughout their desert journey, God will support the people of Israel with miracles and prophetic revelation, but they will also begin to understand and control their environment in ways that they were not free to do as slaves.
Even after the fading of prophecy, the dynamic interplay of revelation and personal observation continues into the Talmud. Rabbi Shimon Ben Chalafta was known as an “askan b’dvarim,” literally, a person who is involved with objects, as opposed to the usual Rabbinic focus on words. He performed experiments, some of them much closer in design to modern experiments than those devised by ancient Greek naturalists. The Talmud (Chullin 56b) describes an experiment that he performed to test the accuracy of Rabbi Yehudah’s claim that a bird whose feathers have fallen out is not kosher because it is mortally ill. The Talmud’s discussion seems to accept the result of this experiment as proof. This is very unusual; attempts to resolve debates in the Talmud almost always appeal to logic, Biblical proof texts, or other rabbinic statements. The success of Rabbi Shimon’s novel scientific approach seems to have gone to his head: He responds to this victory by performing another experiment to test the truth of a statement in the Book of Proverbs. The sages draw the line at this point: In addition to criticizing his experimental design, they insist that empirical testing of Biblical statements is irrelevant and forbidden.
What was this wood that sweetened the bitter waters of Marah? In the midrashic work known as the Mechilta d’Rabbi Ishmael (Masechet Vayisa 1), several Talmudic rabbis weigh in on this question, offering identifications of the tree that give various theological meanings to the incident. Rabbi Yehoshua suggests that it was a willow. This tree is very sensitive to drought and is usually found close to rivers or lakes. Its presence at Marah would suggest that the water there was plentiful, though it needed Moses’s intervention and God’s guidance to be made potable. This may be meant as an example of how human actions with Divine guidance can improve the world. Rabbi Elazar HaModa’i suggests that the wood came from an olive tree. Raw olives were widely known in the Middle East to be inedibly bitter, making the sweetening of the bitter waters of Marah by olive wood a greater miracle. The idea is similar to the frequently cited paradox of the parah adumah (red cow) of Numbers 19, whose ashes purify the impure and contaminate the pure. Rabbi Yehoshua ben Karchah’s opinion that the wood came from ivy plants (also bitter) may express a similar idea and extend it: Ivy was a Greek symbol of victory. Just as the bitter ivy paradoxically sweetened the bitter waters of Marah, Rabbi Yehoshua ben Karchah may have intended that the wisdom imparted prophetically to Moses also sweetened the alien spirit of Greek wisdom, modifying it and making it “kosher.” Rabbi Natan identifies a cedar tree as the source of the purifying wood. The cedar often appears in Biblical metaphor as a symbol of strength, majesty, or even arrogance, but its role in the purification of those who have come in contact with the dead is probably more significant here, and explains Rabbi Natan’s opinion as similar in meaning to the others quoted in this Midrash. The Midrash also includes an anonymous opinion that the wood came from the roots of fig and pomegranate trees, two of the seven species that would later be designated as the ones that may be brought to the Temple as the first fruits that represent the dependence of the land and nation of Israel on God.
Finally, the mystic Rabbi Shimon bar Yocha’i takes a different approach. He does not identify the species of tree involved. Instead, he points out that the Torah does not say that God showed Moses a specific tree (Hebrew “vayar’ehu), but rather that He instructed Moses about it (Hebrew “vayorehu”). Rabbi Shimon seems to see this revelation as more in line with an edict (Hebrew “chok”) than a judgment (“mishpat”). The inclusion of this somewhat different opinion enables the Midrash to embody the dialectic of revelation and experience that the Biblical story reflects.
Many thanks to Rabbi Yosef Weinstock of Hollywood, Florida for introducing me to Rabbeinu Bechaye’s comments on the incident at Marah.