This pasuk introduces the plague of Locust. Hashem tells Moshe that with this plague He will toy with Paroh and his nation. The apparent meaning is that Hashem will humiliate Paroh and the Egyptians. Why was this plague more degrading than those that preceded it?
There is another interesting issue raised by the plague of Locust. The essential affect of this plague was that locusts would consume all grain and produce that had survived the plague of Hail. Egypt would experience severe famine. In order for Paroh to rescue his people from this plague, he would need Moshe’s immediate intercession. Once the crops were consumed, the devastation of the plague would be complete.
As the damage of the plague was afflicted, Paroh withstood calling for Moshe and Ahron. Only after the crops had been totally destroyed, did he beseech Moshe and Ahron to pray on his behalf. Paroh had already persevered through the worst of the plague. Why break down at this point?
One interesting approach to these problems posits that these two questions are interrelated. Let us begin by understanding Paroh’s reason for seeking relief from the plague after the locusts had already consumed the crops and produce of the land.
Paroh withstood the destruction of the plague without weakening. However once the locusts had ravaged the land, he was confronted with a scene of total destruction. This landscape of devastation overwhelmed Paroh. Paroh knew he could not reverse the damage of the plague. But he had to have relief from the sight of locusts. This was his reason for beseeching Moshe and Ahron to pray on his behalf.
This is not the behavior of an individual who is in control. It is characteristic of an emotionally shattered person, unable to bear even a reminder of his misfortune.
Now we can answer our first question. In what way was this plague more degrading that those that preceded it? The first seven plagues never broke Paroh emotionally. He was able to retain his self-respect. On occasion, the pressure of a plague forced him to promise Bnai Yisrael freedom. But with the cessation of each plague, Paroh quickly regained his confidence and sense of control.
The plague of Locust was different. The devastation of this plague shattered Paroh. He called for Moshe and Ahron even though he could no longer reverse or even suspend the damage. He needed Moshe and Ahron to relieve the pain of seeing the locusts – the reminder of his folly and demise. This is the degradation referred to in the opening pesukim.
“But among Bnai Yisrael a dog will not bark at a man or animal. This is so you will know that Hashem has distinguished between the Egyptians and the Israelites.” (Shemot 11:7)
Moshe tells Paroh of the final plague. Hashem will strike the firstborn of the Egyptians. This terrible plague will fall upon Paroh’s own son. It will even destroy the firstborn children of the Egyptians’ servants. Only the firstborn of Bnai Yisrael will be spared.
Moshe adds that at the time of the plague, complete peace will prevail among Bnai Yisrael. He asserts that even the dogs will refrain from snapping at other animals or strangers. Moshe explains that the unusual behavior of the dogs will demonstrate that the Almighty distinguishes between the Egyptians and Bnai Yisrael
Moshe’s comments are difficult to understand. Moshe explains that Hashem will destroy the firstborn of the Egyptians. The plague will extend from the firstborn of Paroh to the firstborn of the Egyptians’ servants. Only Bnai Yisrael will be spared. Clearly, the exclusion of Bnai Yisrael from this horrible plague will demonstrate Hashem’s special treatment of Bnai Yisrael. However, Moshe adds that, among Bnai Yisrael, even an unfriendly dog will not disturb the peace. He then asserts that the unusual docile behavior of the dogs will demonstrate the Almighty’s preferential treatment of Bnai Yisrael. True, this animal behavior is unusual. However, it is not nearly as remarkable as the pattern of the plague. The fact that this pervasive death would not touch Bnai Yisrael is far more remarkable than the silence of the dogs! Why does Moshe insist that the behavior of the canines is so impressive?
We will consider two approaches to answering this question. The first approach requires that we carefully consider the impact of this plague upon the Egyptians. What effect would the plague of the firstborn have upon the Egyptian people? Obviously, this plague would bring widespread death upon the Egyptians. However, Moshe stresses another impact. He explains that the Egyptian people will be thrown into a state of complete panic and despair. He tells Paroh that the cries of the people will exceed anything in the past or future. Total chaos will reign. In short, Moshe described two impacts. First, the firstborn will die. Second, the Egyptians will be thrown into a state of complete panic and despair.
Now, we can provide an explanation of Moshe’s comments. Why did Moshe refer to canine behavior? Moshe wanted to contrast the experience of Bnai Yisrael during the plague of the firstborn to the experience of the Egyptians. As we have explained, the plague would impact upon the Egyptians in two ways. It would bring widespread death. It would create intense panic and despair. Moshe contrasted the experience of Bnai Yisrael to that of the Egyptians in both of these areas. He explained that while the firstborn of the Egyptians would die, the firstborn of the Jewish people would pass the night unharmed. Then, he explained that, whereas panic and despair would overrun the Egyptians, Bnai Yisrael would experience complete calm and peace. Moshe contented that this contrast would demonstrate the complete separation between Bnai Yisrael and the Egyptian people.
The second approach requires that we briefly discuss the concept of contrast. Contrast is the greatest between opposites. For example, we can contrast a brilliant person with an individual of normal intelligence. A certain degree of contrast does exist between these two individuals. However, greater contrast emerges when we compare opposites. In our example, if we compare the brilliant person, and an extremely dull-witted individual, a greater level of contrast emerges.
Hashem wished to create the greatest possible level of contrast between Bnai Yisrael and the Egyptians. Some level of contrast would emerge simply because Bnai Yisrael would be excluded from the plague. However, this is not the highest possible level of contrast. A greater degree of contrast emerges, when opposites are compared. Therefore, Hashem created an uncommon climate of peace among the people of Bnai Yisrael. This is the opposite of the state that would exist among the Egyptians. This would enhance the contrast between the experiences of the two nations.
“This month shall be for you the first of the months. It shall be for you the first of the months of the year.” (Shemot 12:2)
This passage introduces the commandment to establish a calendar. Each festival is assigned a date on this calendar. Hashem tells Moshe that the first month of the calendar is Nissan. This is the month that Bnai Yisrael will leave Egypt.
There is an interesting midrash on this pasuk. An introduction is needed to understand the midrash’s comments. The calendar established by the Torah is lunar. This means that new months are declared on the basis of the appearance of the new moon. Ideally, the new month is declared on the basis of the testimony of two witnesses. These witnesses appear before the high court in Yerushalayim and declare that they have seen the crescent. It is true that the appearance of the new moon can also be calculated mathematically. However, in the ideal situation the mathematical calculations only play a secondary role. The primary basis for declaring the new month is through eyewitness testimony.
Today we do not have a high court. Therefore, we cannot determine the advent of a new month on the basis of testimony. Instead, we rely on mathematical calculations. The Jewish calendar is the result of these calculations.
The midrash explains that Moshe had difficulty understanding this mitzvah. In order to solve Moshe’s problem, the Almighty showed Moshe the exact crescent shape that must be seen by the witnesses. He explained to Moshe that when this is seen, the new moon is declared.
The apparent meaning of the midrash is that Moshe could not visualize the amount of a crescent that the witnesses must see. He wondered, “How much of a crescent must be seen in order for the new month to be declared?”
This interpretation of the midrash and Moshe’s question presents a problem. It seems from this interpretation that the new month cannot be declared on the basis of the appearance of a minimal crescent. However, this interpretation of the midrash is not possible! Any minimal appearance of the moon is adequate. There is no standard that must be met. If the witnesses testify that they have seen the new moon, a new month is declared. There is no requirement regarding the size of the crescent!
Let us consider a related issue. Now, that there is no court in Yerushalayim the new month is determined through mathematical calculations. This raises an interesting question. What is the exact definition of a new month? The obvious answer is that the new month is defined by the appearance of the new moon. Therefore, the new month begins on the first evening that the new moon appears. The calendar need only calculate this date. However, this answer ignores an important problem. In order to understand this problem, some background information is needed.
The moon does not generate its own light. The light of the moon is actually the reflected light of the sun. When the moon and sun are exactly in alignment, the illuminated side of the moon faces away from the earth. As the moon begins to distance itself from this alignment with the sun, the crescent of the new moon appears. However, the crescent does not appear immediately. Some amount of time is required after the disjunction of the sun and moon for the crescent of the new moon to appear. The amount of time depends on the location of the observer on earth. In Yerushalayim, six hours are required. Therefore, if the disjunction occurs before midday, the crescent will appear immediately with nightfall. If it occurs after midday the crescent will not appear immediately at nightfall.
Now, we can appreciate the problem posed by mathematically calculating the date of the new month. When does the new month begin? This requires an exact definition. Is the new month initiated by the disjunction of the moon and sun? Alternatively, is the new month determined by the actual appearance of the new crescent in the skies above Yerushalayim?
Maimonides deals with this issue. He explains that the calendar calculations determine the moment that the crescent appears. This answers our question. The new month is not defined by the disjunction of the sun and moon. It is defined by the appearance of the crescent.
Rav Yitzchak Zev Soloveitchik Zt”l explains that this was Moshe’s question. What is the precise definition of the new month? Hashem showed Moshe the crescent of the new moon. He told Moshe you must see this and then sanctify the new month. The Almighty explained that the disjunction of the sun and moon does not create a new month. The actual appearance of the new crescent creates the new month.
 Michilta, Parshat Bo, Chapter 1.
 Rav Yechiel Michal HaLeyve Epstein, Aruch HaShulchan HaAtede, Hilchot Kidush HaChodesh 88:12.
 Mesechet Rosh HaShannah 20b.
 Rabbaynu Moshe ben Maimon (Rambam / Maimonides) Mishne Torah, Hilchot Kiddush HaChodesh 7:2. See also Rav Yechiel Michal HaLeyve Epstein, Aruch HaShulchan HaAtede, Hilchot Kidush HaChodesh 88:12.
 Rav Yitzchak Zev Soloveitchik, Chidushai MaRan RIZ HaLeyve on the Torah, Parshat Bo.