Persian law, remember, confined the wives of the kingdom to the authority of their husbands. It was feared that Vashti’s refusal to appear before the king would lead to a kind of woman’s liberation movement in the kingdom, especially among the nobility, thus causing interference in public affairs (Esther 1:17-20). So, it would seem that it was believed that the less wives knew of public matters, the more men would be enabled to carry out their own affairs, “both great and small.” Therefore, while secluded in the king’s harem, it isn’t likely that Esther knew the reason behind Mordecai’s recent change of circumstances (Esther 4:1-2). Moreover, because he refused her efforts to permit him to enter the king’s gate, it made it more difficult to gain the information she desired (Esther 4:4).
Considering the fact that Mordecai had refused to carry on a discussion of his affairs in a more private venue, vis-à-vis within the king’s gate, the discussion between Esther and Mordecai would have to be conducted in the street of the city (Esther 4:6), meaning in the public square. Esther had several eunuchs given her by the king to serve her needs. One of them, Hatach, was trusted to carry her messages to Mordecai and his to her (Esther 4:5). Apparently, therefore, Hatach probably knew the secret of the queen’s national identity (cp. Esther 2:10, 20), which may be because he was a Jew, himself. If not, he certainly would have become aware of it, during the discussion between Esther and Mordecai. In either case, he would have been considered trustworthy, so he was sent to Mordecai in order to discover the reason behind his present state of affairs, and why he refused to accept the queen’s offer of a change of clothing, which would have permitted their discussion to be carried out more privately.
When Hatach arrived, Mordecai told him everything that had happened, including the detail about the sum of money Haman had promised the king,[1] if he permitted the destruction of the whole Jewish nation, which was scattered throughout his kingdom (Esther 4:7). It seems that the sum of money was of particular importance in Mordecai’s discussion with Esther. Why would that detail be important, unless the sum was an estimate of the Jews’ total worth in terms of it being a spoil for the king. So, if the Jewish nation had property worth that much, selling it to the king’s servants would add that amount to the king’s treasury! Therefore, Mordecai also gave Hatch a copy of the king’s decree, so it could be shown to Esther. Moreover, Mordecai charged Esther, through Hatch, to go to the king, revealing her Jewish identity, and make a request of him for her people (Esther 4:8). So, Hatch did as Mordecai requested and told the queen everything that was told to him (Esther 4:9).
______________________________________________________________
[1] The text doesn’t record how Mordecai knew about the sum of money that was promised the king (Esther 4:7). However, if Haman’s promise to put 10,000 talents of silver into the king’s treasury (Esther 3:9) was the product of the spoil of the Jews’ property once the whole nation was slain (Esther 3:12-13), then that detail would have been written in the decree which Mordecai had in his possession (Esther 4:8).