Why do the Makos follow a set pattern? In the first out of each set of three Makos, Moshe confronted Pharaoh at the Nile; in the second, it was at the palace; whereas the third (such as this plague of Shechin) had no warning at all?
Refer to 7:14:8:2, regarding the Makos' breakup into the categories De'tzach, A'dash, Be'achav.
What is the definition of "Pi'ach Kivshan"?
Rashi and Targum Onkelos: 'Soot from a furnace'.
Rashbam and Targum Yonasan: Fine ashes from a furnace.
What are the connotations of "Sh'chin Pore'ach Ava'bu'os"?
Rashi, Targum Onkelos and Targum Yonasan: 'Boils 1 that grow into blisters'.
Rashi: The root of the word is 'Shichnah' - heat, as in Yoma 53b 'Shanah Shechunah'.
How could Moshe both throw his and Aharon's double hands-full of soot, up into the sky (see Sifsei Chachamim), with force?
Why did this Makah involve three participants - Aharon held ashes, Moshe threw it, and Hashem scattered it over all of Egypt?
Why did Hashem instruct Moshe to throw the soot "in front of Pharaoh," something he did not do by Kinim and Choshech (the other Makos that came without a warning)?
Seforno: So that Pharaoh would know that it was sent by Hashem, and not a natural plague caused by the elements - which sometimes occurs.
Oznayim la'Torah (to 9:10): So that Par'oh should know that it came about through Moshe - bearing in mind that he did not warn Par'oh in advance. In fact, Kinim and Choshech were also done in front of Par'oh, for the same similar reason - even though the Torah does not mention it.
Why, by the plague of Shechin, was Moshe told to throw soot from a furnace - in place of using the staff, which he used to bring on all the other plagues?
Oznayim la'Torah: Because the four fistfulls of soot from the furnace reminded Hashem of the Mesiras Nefesh of four Tzadikim 1 who would sanctify Hashem's Name by being cast into a furnace - Avraham, Chananyah, Misha'el and Azaryah. 2 They served as a merit for Yisrael to be redeemed, and as an example for them to follow.
Why does the Torah write "Kechu Lachem" only regarding boils?
Moshav Zekenim: Because, whereas the key elements of the other Makos already existed, and they only needed to be brought to Egypt, the boils did not come from anywhere else. 1
Because it was the only Makah which required using another item to bring on the plague.
Moshav Zekenim: Since if someone (elsewhere) was destined to have boils, Hashem would not take them away from him to bring them to Egypt.
QUESTIONS ON RASHI
Rashi writes: "'Moshe shall throw it' - Something thrown forcefully must be thrown with one hand." But what indicates that these ashes should be thrown with force?
Gur Aryeh: The term 'Zerikah' itself (as opposed to 'the term Hashlachah' - to cast) means a forceful throw. Chazal use the term 'Zorek' for shooting an arrow (Kesuvos 31a), or throwing a stone (Sanhedrin 60b).
