Dr. Stephen Newman has degrees in chemical engineering and physical chemistry. His biog-raphy appears in Who’s Who in Science and Engineering, Who’s Who in America and Who’s Who in the World.

At Moses’ encounter with the Burning Bush, God charged him to be his messenger in emancipating the Israelites from Egypt. Moses questioned, What if they do not believe me and do not listen to me, but say ‘The Lord did not appear to you?’ (Ex. 4:1). God provided Moses with three signs that they may believe that the Lord, the God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, did appear to you (Ex. 4:5). The first was turning Moses’ rod into a snake, the third was turning water from the Nile into blood. For the second sign, Moses was told ‘Put your hand into your bosom.’ He put his hand into his bosom and when he took it out, his hand was encrusted with snowy scales (Ex. 4:6). But when he put his hand back in and out of his bosom, there it was again like the rest of his body (Ex. 4:7). Miraculously Moses’ hand was restored to normal.

In fact, Moses did display these signs to the Israelites (Ex. 4:30), and used the first and third to demonstrate the power of God to the skeptical Egyptians as well (Ex. 7:8ff). What is the significance of the second feat, and why was it the only sign not performed later for the Egyptians?

Exodus Rabbah 3:17 explains that the second sign was meant to chastise Moses. Traditionally, leprosy is the punishment for speaking slander (lashon hara), and Moses was so punished because he stated that the Israelites and their leaders would not believe what God had said. The first sign was also understood in the midrash to be chastising Moses for the same transgression, as the rod turning into a snake was intended to recall the serpent in the Garden of Eden who also sinned through his speech. Based on this, Midrash Lekah Tov here notes that the first two signs were really directed at Moses personally, and only the third sign, water turning into blood, was meant as the sign to be shown publicly in case Moses was not believed.


If we refer to extra-biblical literature, we can further understand the reference to Moses’ leprosy. Manetho (circa 300 BCE) was an Egyptian historian. His text, Aegyptiaca, was researched and written at the request of Pharaoh Ptolemy I as a record of all pharaohs and as a history of Egypt. Josephus, the Jewish historian (37-100 CE), had access to the text and quoted extensively from it, but it is no longer available in its original form.

Josephus quotes Manetho in his work Contra Apion in order to discredit Manetho’s version of the Exodus. In Aegyptiaca, Pharaoh Amenophis is counseled to purge Egypt of all lepers and other polluted persons. The afflicted Egyptians, 80,000 in total, are rounded up and sent to work in stone quarries. They are also moved into the abandoned city Avaris, thus effectively keeping them quarantined. A renegade Egyptian priest, Osarseph from Heliopolis, became the leader of the slaves. Manetho described him as leprous. Osarseph commanded the slaves not to worship Egyptian gods, nor to refrain from eating and sacrificing animals sacred to the Egyptians, and to have intercourse only with their own people, among other laws. Manetho noted that Osarseph changed his name to Moses upon joining with the slaves. The slaves rose up and rampaged throughout Egypt, burning cities, plundering temples and destroying images of the Egyptian gods.1

This report is generally considered an example of Egyptian hostility towards Jews and their culture, and this is how Josephus relates to it. He goes on to discredit it, as it is based on invented stories and rumors.2

Classifying Moses as an Egyptian priest is not as outrageous as one might think at first glance. Egyptian priests were appointed by pharaohs and frequently were members of the royal family. The Egyptian priesthood was a center of learning and a repository of knowledge. The priests were knowledgeable in many subjects, including geometry, astronomy, philosophy and mathematics. Three of the temples (Heliopolis, Thebes and Memphis) were academies, elite institutions.3 Recalling that Moses was an adopted son of an Egyptian princess, Moses would have been readily qualified to be a member of an academy; it is possible that it was in this intellectual environment that Moses spent many of his years not accounted for in the Bible.

Similarly, the idea that Moses had an Egyptian name is not unusual, as the Bible credits Pharaoh’s daughter with naming Moses in Exodus 2:10. Many years earlier Joseph was given the name Zaphenath-Paneah by Pharaoh and was given in marriage to Asenath, daughter of Potiphera, priest of On (Gen. 41:45).

What about the leprosy element which is such a prominent element of the Manetho account? Leprosy as such was not reported in Egypt until the Greek period,4 but the identification of the biblical tzara’at with leprosy is inaccurate, it would be more correct to identify it with skin disease in general.5 “A potent strain in Egyptian literature fastens blame for evils suffered by the populace on the impure and the diseased.”6 There is some evidence that in Egypt individuals with severe skin conditions were generally considered excluded from the afterlife.7

In light of this, the sign of Moses being healed from a skin disease may contain a message that while the Egyptians treat the Israelites as a source of trouble (Ex. 1:10), in fact the Israelites are pure and blameless. In this sense the sign is meant to inspire the Israelites to reject the status accorded to them by the Egyptians, as a step towards emancipation. Later, in Exodus 14:12, we find Israelites complaining that it would be better for us the serve the Egyptians; the slave mentality was not easily eradicated. Based on this, we can understand why a version of this sign was never used for the Egyptians, as it was meant only as an internal Israelite wonder, with the uplifting message that they rise above any sort of perceived impurity.


  1. Erich S. Gruen, Heritage and Hellenism (Berkley: University of California Press, 1998) pp. 57-58. See there a long discussion of the Manetho account and its interpretation.
  2. Josephus, Contra Apion 1:229.
  3. Serge Sauneron, The Priests of Ancient Egypt (Ithaca, New York: Cornell University Press, 2000) p. 61.
  4. John F. Nunn, Ancient Egyptian Medicine (Norman, Oklahoma: University of Oklahoma Press, 2002) p. 74.
  5. Samson Olanisebe, “Laws of Tzara’at in Leviticus 13-14 and Medical Leprosy”, Jewish Bible Quarterly 42:2, April 2014, pp. 121-127.
  6. Gruen, p. 60.
  7. Stephen Quirke, Exploring Religion in Ancient Egypt (West Sussex: John Wiley and Sons, 2015) p. 47.

I dedicate this paper to my family, in particular my wife Mary Ellen and daughters Sharon and Lori.

I thank Rabbi Mark Mallach, and his Torah study group, for providing me inspiration.