Thicker than Water

Thicker than Water

by Eliezer Segal

As the traditional Jewish commentators scrutinized the Bible with their characteristic thoroughness, they could not help but be struck the diversity of the ten plagues that were inflicted upon the Egyptians. 

Some of the plagues, such as the fiery hailstones and the precise targeting of the Egyptian firstborn, were hard to explain as anything other than supernatural marvels. However, most of the others, including the assorted human and animal diseases, were outwardly indistinguishable from natural phenomena, and their miraculous status was manifest only in their opportune timing and in their being foretold by Moses and Aaron.

The Passover Haggadah, for the most part, reflects the typical approach of the talmudic and midrashic preachers who delighted in magnifying the miraculous dimensions of the plagues. This approach is evident, for example, in that familiar passage where Rabbis Yosé the Galilean, Eliezer and Akiva vie to outdo each other in counting how many afflictions were really compressed into the ten plagues of Egypt and the splitting of the Red Sea.

The first of the ten plagues, the transformation of the Nile’s waters into blood, is situated midway between the extremes of the purely naturalistic and the outright miraculous. A straightforward reading of the biblical narrative favours a distinctly supernatural interpretation of the event, since water (at least before the advent of modern industrial pollutants) does not normally mutate itself into an organic substance like blood. 

The rabbis of the Midrash followed their usual policy of multiplying the supernatural aspects of the plague, introducing novel details into the story beyond those provided by the Torah. For example, some sages asserted that not only did blood flow in the lakes and rivers, but it even issued from the Egyptian idols. Others related how the liquid remained crystal-clear and drinkable when it was poured by the Israelites

During the Middle Ages, many Jewish thinkers were deeply influenced by the rationalistic approaches of the Greek philosophical tradition, and they sought to apply scientific principles to the understanding of Scripture.

From the perspective of the Jewish philosophers, the greatness of God can best be appreciated by means of an intensive study of the unchanging and intricate laws of nature. For this reason, they were usually reluctant to acknowledge any suspensions of the natural order. 

In contrast to the Talmudic sages, for whom the proliferation of miraculous events served to exalt the infinite power of the Almighty, the medieval rationalists believed that superfluous miracles actually diminished the stature of the omnipotent and eternal Creator who had established the laws of nature.

It was no easy task for them to propose scientifically plausible explanations for the plague of blood. 

Take for example the difficulties faced by the fourteenth-century French commentator Rabbi Nissim of Marseilles. As a matter of general principle, he declared that the plague of blood should not be classified as a nes, a truly supernatural miracle, but rather as a mofet (“sign”), a natural process whose imminent occurrence was predicted by Aaron thanks to his expertise in reading the evidence of the stars. 

Even Rabbi Nissim had to acknowledge that the change that affected the water was a drastic one, since the Torah states that the water remained utterly undrinkable for seven days. He argued that the transformation was achieved by means of the intensity of the sun, which rendered the waters red, thick and putrid. Water of that sort provided a natural breeding environment for the frogs who would show up for the next plague.

Even some authors with clearly philosophical sympathies admitted that the Torah’s plain sense was undeniable in this instance, and that that the Nile underwent a bona fide chemical mutation from water to real blood. 

Maimonides, who was usually very reluctant to acknowledge changes in the natural order, stressed that the change was only a temporary one that left no lasting effects. 

The impermanence of the water’s altered state was also underscored in the commentary of the thirteenth-century French exegete Rabbi Hezekiah ben Manoah (the Hizzekuni): “The transformation of the Nile into blood was only for a specified time, causing the fish to perish instantly on account of the blood. Afterwards, the Nile reverted to its original state.” 

In a similar vein, the French philosopher and exegete Gersonides, while accepting the literal implications of the episode, stressed that the potentiality for such an “exception” had been programmed into nature at the time of the universe’s inception, and therefore did not constitute a violation of the natural order. 

Another Jewish scholar who tried his hand at scientifically analyzing the plague of blood was Rabbi Abraham Farisol, a16th-century philosopher who wandered from Avignon in southern France, settling eventually in Ferrara, where he was involved in the lively intellectual life of the Renaissance. In addition to his prolific output of Bible commentaries and inter-religious polemics, he is known primarily for his influential geographical treatise, Orhot Olam.

Farisol found it impossible to accept the biblical story at face value. As a scientist, he had very clear ideas about the physical nature of blood, as a substance that is found exclusively in living creatures that take nourishment. It was obvious to Rabbi Farisol that there is no scientific process by which simple H20 can be changed into an organic substance. Therefore, he concluded, what the Egyptians experienced must have been an elaborate optical illusion with a symbolic message. By causing the water to decay and assume a red form, the Egyptians were being issued a metaphoric forewarning of the death lay in store for them in the forthcoming plagues.


It is intriguing to speculate about how these Jewish savants of yore conducted their seders. When the time came to recite the ten plagues, they might well have supplemented their Haggadot and traditional commentaries with chemistry textbooks, and perhaps even a few kosher-for-Passover flasks and test tubes. 

They might eventually have reached an agreement in their disputes over the correct interpretation of Exodus story. 

And agreement among Jewish scholars would have been the greatest of miracles.


  • First Publication:
    • The Jewish Free Press, Calgary, March 27, 2003, pp. 12-13. 
  • For further reading:
    • Heinemann, Isaac. Darkhei Ha-‘Aggadah. Jerusalem and Tel-Aviv: Magnes and Masadah, 1970.
    • Kreisel, Haim. “The Torah Commentary of R. Nissim Ben Mosheh of Marseilles: On a Medieval Approach to Torah U-Madda.” The Torah u-Madda Journal10 (2001): 20-36.
    • Kreisel, Howard T., ed. Liber Ma’Ase Nissim: Perush La-Torah Le-R. Nisim Ben Mosheh Mi-Marseilles. Jerusalem: Mekitse Nirdamim, 2000.
    • Roth, Cecil. The Jews in the Renaissance. Philadelphia: Jewish Publication Society of America, 1977.
    • Ruderman, David B. The World of a Renaissance Jew: The Life and Thought of Abraham Ben Mordecai Farissol Monographs of the American Jewish Archives. Cincinnati: Hebrew Union College Press, 1981.
    • Sirat, Colette. A History of Jewish Philosophy in the Middle Ages. Cambridge, England: Cambridge University Press, 1985.

Prof. Eliezer Segal

This article is included in the collection Sanctified Seasons, the Alberta Judaic Library, 2008.