Adapted to English from the Sefer Be’er Yosef by Rav Yosef Tzvi Salant.
Esther called to Hasach, one of the king’s attendants who was assigned to assist her, and commanded him regarding Mordechai, to know what this was, and what this was about. 
After Haman and Achashverosh’s harsh decree to exterminate the Jews was made known, Mordechai tore his clothes in mourning.  He wore sackcloth and ash. His relative, Esther, who was now the Queen of Persia, heard what Mordechai was doing. This distressed her very much. She sent an attendant to inquire of Mordechai about what he was doing, for she was unaware of the recent decree. The Megillah uses an interesting expression to describe her inquiry:
“מה זה ועל מה זה” – “[Esther asked], ‘What was this and what was this about?’”
Our Sages homiletically read these two “מה זה” as two מזה””  and therefore connect them to the verse of “the Tablets containing the Ten Commandments were engraved from both sides; they were engraved through and through.”  Esther was alluding to another question she posed to Mordechai: Why are you doing this? Perhaps the Jews transgressed the five books of the Torah, of which it is written, “they were engraved through and through?”
Now, it requires clarification what her intent was in mentioning that the Torah is engraved “through and through.” What does it add that the Ten Commandments, representing the Torah,  were engraved this way? What difference does it make? Furthermore, why did she stress “the five books of the Torah?” Why not just ask if the Jews transgressed the Torah?
One explanation can be suggested based on a discussion the Gemara has regarding the root cause of Haman’s decree.  The students of Rabbi Shimon bar Yochai asked him: Why were the Jews sentenced to complete annihilation? He responded by asking his students to offer a suggestion. They said it was because they benefited from the feast of Achashverosh. He responded that that would explain why the Jews in Shushan should be sentenced to death, but why were the Jews in the rest of the world given the same sentence? He suggested that it was because they bowed to Nebuchadnezzar’s idol. His students asked how Hashem could then show them favoritism and spare them? He responded that although they outwardly bowed to the idol, it was only for show. They didn’t mean it. As well, when Hashem orchestrated the decree, it was only for show.
However, alternate versions of this dialogue show that it was Rabbi Shimon bar Yochai who suggested their sin was benefiting from Achashverosh’s feast.  Why then were the rest of the Jews sentenced to death? Because all Jews are responsible for one another. 
Based on Be’er Yosef, Esther 4:5, printed after sefer Shemos.
 Esther loc. cit.
 Ibid. v. 1.
 Megillah 15a.
 Shemos 32:15.
 See Rashi, Shemos 24:12, quoting Rav Saadiah Gaon, that all the 613 mitzvos are included in the Ten Commandments. Rav Saadiah Gaon in his siddur actually categorized all the 613, indicating which of the
ten they fall under. See also Baal Haturim, ibid. 20:14, quoting Bamidbar Rabbah 13:16.
 Ibid. 12a.
 Shir Hashirim Rabbah 7:13.
 See Toras Kohanim, Vayikra 26:37; Sanhedrin 27b.
OlamiResources.com is greatly appreciative to Rabbi Refael Wolfe for sharing this chapter from his important recent sefer, Be’er Yosef – Selected Writings of Rav Yosef Tzvi Salant. Please click here to purchase. Rabbi Wolfe is originally from Ottawa, Canada and earned a Bachelor of Computer Science from Carleton University and a Master’s in Talmudic Law from Ner Yisrael Rabbinical College. He has studied in Yeshivas Darche Noam/Shapell’s; Mir Yerushalayim; Ner Yisrael, Baltimore; and Kollel Oholei Yom Tov, Toronto. He currently lives with his family in Yerushalayim and is learning in the Ohr Lagolah Semicha Kollel. He writes a weekly devar Torah email called “Parsha Ponders.” Select pieces from this series have been compiled into a sefer with the same name. Archives of previous emails can be viewed at https://parshaponders.com.