Parashat Vaera describes in great detail the first seven of the Ten Plagues. The fifth plague is the plague of Dever – a pestilence or an epidemic that caused the destruction of the Egyptian livestock [Shemot 9:6]: “Hashem did this thing… and all the livestock of the Egyptians died”. Wait a minute – did we just say that all of the livestock died? Every last one of them? Let’s fast forward to the exodus. Am Yisrael find themselves trapped with the Red Sea on one side and the Egyptian Army on the other [Shemot 14:9]: “The Egyptians chased after them and overtook them encamped by the sea; every horse of Pharaoh’s chariots, his horsemen, and his force”. Where did Pharaoh get the horses from to pull his chariots? Weren’t they all dead? Rashi offers a systematic answer to this question: The horses couldn’t have belonged to the Egyptians because they all died in the plague of pestilence. They couldn’t have belonged to the Jews because the Jews took all their animals with them. Rashi concludes that the horses belonged to the few Egyptians who believed in Hashem. Just as their animals were (explicitly) spared in the plague of hail, their animals were also spared in the plague of Dever.
The Ralbag takes a different approach, teaching that sometimes the word “all” doesn’t mean “all”. Sometimes “all” is only a figure of speech, meaning “most”. He brings a number of examples from the Torah where this rule holds. Obviously, if we implement the explanation of the Ralbag, all of our questions go away: Pharaoh chased after Am Yisrael with whatever few animals survived the Ten Plagues. Nevertheless, one question still remains: If “all” doesn’t mean “all”, why does the Torah insist on using the word “all”? Why doesn’t it just say “most of the animals died” or just “the animals died”?
To address this question we require some background. Most of the commentators explain that Hashem didn’t strike the Egyptians with ten random plagues. Each plague contained a message, either for the Egyptians, for Am Yisrael, or for both of them. What was the message of the plague of Dever? Let’s take a look at the verses [Shemot 9:3-7]: “The hand of Hashem will be upon your livestock that is in the field, upon the horses, the donkeys, the camels, the cattle, and the sheep, a very severe epidemic. Hashem will make a separation between the livestock of Israel and the livestock of Egypt, and nothing of the Children of Israel will die… Hashem did this thing… and all the livestock of the Egyptians died, but of the livestock of the Children of Israel not one died. Pharaoh sent, and behold, not even one of the livestock of Israel died, and Pharaoh’s heart became hardened and he did not let the people out.” To summarize:  Hashem says that He will differentiate between the Egyptians and the Jews,  only the Egyptian livestock are hit by the plague,  Pharaoh notes this, yet even so  he refuses to release the Jews. It seems clear that the key word here is “separation”: Only the Egyptian livestock was affected. Imagine two cows grazing one next to the other. One cow is owned by an Egyptian slave-owner and the other by a Jewish slave. One cow drops dead and the other continues grazing. Given what we know today about the transmission of viral and bacterial disease, this scenario appears highly unlikely. And while the Egyptians were unfamiliar with the mechanism of the transmission of disease, they surely must have known about contagion: animals that live together tend to die together. The fact that this did not occur in the plague of Dever sent a message.
And yet, it is difficult to claim that is the message of the fifth plague is “separation”. The reason is that Hashem gave the exact same message in the fourth plague, the plague of Arov (wild animals) [Shemot 8:17-18]: “For if you do not let My people go, behold, I will incite against you, your servants and your people and in your houses a mixture of noxious creatures, and the houses of Egypt will be filled with the mixture of noxious creatures, as well as the land upon which they live. I will separate on that day the land of Goshen, upon which My people stand, that there will be no mixture of noxious creatures there, in order that you know that I am Hashem in the midst of the earth.” In order to create separation between Jew and Egyptian, the snakes, the scorpions and the lions were given “no-fly-zones”. But if “separation” was the message of the fourth plague, what was the innovation of the fifth plague?
To answer this question, we introduce a concept from the field of thermodynamics called Entropy. Entropy is the measure of disorder and randomness in a system. By definition, the greater the disorder, the higher the entropy. For example, a messy room has higher entropy than a clean room. The second Law of Thermodynamics says that the entropy of an isolated system will tend to increase over time. What this means is that a system tends towards disorder. A clean room will tend to become messy while a messy room will not tend to become clean, unless somebody comes along and puts away the toys and clothing that is strewn all over the floor. Similarly, dishes tend to break and chip, while fixing broken dishes is a chore. Entropy affects everything: from information to economics to the human thought process. If you want order, you’re going to have to work for it.
Now let’s take a closer look at the plague of Dever:
- “Hashem will make a separation between the livestock of Israel and the livestock of Egypt, and nothing (davar) of the Children of Israel will die.
- “All (kol) the livestock of the Egyptians died, but of the livestock of the Children of Israel not one died (echad).”
- “Pharaoh sent, and behold, not even one (ad echad) of the livestock of Israel died.”
The Midrash has something very interesting to say about the phrase “nothing of the Children of Israel will die”. The Midrash teaches that not only did no Jewish animals die during the plague of Dever, but also not one Jew died. Not one Jewish dish broke. Not one Jewish person was sad or depressed. Anything that was in any way connected with death or damage or fracture was stifled. Wherever a Jew lived, the second Law of Thermodynamics was being violated and the entropy was decreasing. This was the message that the plague of Dever: Hashem created the basic physical laws according to which the world runs and He can violate these laws whenever and wherever He chooses.
Now we can understand why the Torah says that “all” the Egyptian animals died. What the Torah meant was that death and all his friends were relegated to the Egyptians. For the Jews death had no meaning or relevance. When Hashem said that “nothing” of the Jews will die, He meant that absolutely nothing will die. With the Jews, “none” meant “none”. The only reason that Hashem killed the Egyptian animals was to highlight what was not happening on the Jewish side of town, where entropy had become persona non grata. But Pharaoh missed the message. Pharaoh was still living in the fourth plague. Pharaoh saw that “not one” Jewish animal died. That happened last time. Been there, done that. And so having seen nothing new, Pharaoh had no reason to let the Jewish people go. Another five plagues would be required until Pharaoh and the Jewish people understood Hashem’s complete and absolute dominion over all.
Ari Sacher, Moreshet, 5775
Please daven for a Refu’a Shelema for Nechemiah Uriel ben Tzipora Hadara and Moshe Dov ben Malka
 See Shemot [10:26]
 See Shemot [9:20]
 Rav Levi ben Gershon, known as “Gersonides”. The Ralbag lived in the 14th Century. His commentary on the Torah takes a highly rational approach to Judaism.
 Parents of young children are exquisitely familiar with this phenomenon.