Hashem gave Moshe three signs to show that he was sent by Hashem to free the Jewish people: (1) the staff turning into a snake, (2) Moshe’s hand getting leprosy and then turning back to normal, and (3) turning water into blood. He showed these signs to the Jewish people as we saw towards the end of last week’s Torah portion of Shemos. But in this week’s portion of Vaera he only shows Pharaoh the wonder of turning the staff into a snake (or crocodile).
The Torah refers to what Moshe showed the Jews as signs, but what he showed Pharaoh as a wonder. The Sforno says that “a wonder comes to demonstrate the greatness of the sender, that it is proper to hearken to His voice. A sign, however, testifies to the authenticity of the messenger. That is why Moshe performed ‘signs’ in the presence of the Jews, who did not doubt the greatness and ability of the Sender but questioned whether the messenger was authentic. Pharaoh, however, had doubts regarding the Sender, and even denied His existence, as he said, ‘I know not Hashem’ (Shemos 5:2). That is why he asks for a ‘wonder’ to authenticate the greatness of the Sender, in a manner which will demonstrate that He is worthy to be listened to. It is not unprecedented for the same object to be used as a sign and a wonder for different people” (Sforno on Shemos 7:9).
The Torah had said right before Moshe’s first confrontation with Pharaoh, “Hashem spoke to Moshe and Aharon, saying, “When Pharaoh speaks to you, saying, ‘Provide a sign for yourselves,’ you shall say to Aharon, ‘Take your staff, [and] cast [it] before Pharaoh; it will become a serpent (crocodile)’ ” (Shemos 7:8, 9). The Chizkuni observes that “this portion was already mentioned in Shemos, ‘see all the signs that I have placed in your hand and perform them before Pharaoh,’ (Shemos 4:21). It was repeated here because of the new thing that happened. What new thing happened? He only performed the staff turning into a serpent (crocodile) before Pharaoh.”
The Chizkuni, explains what a “wonder” is by quoting Rashi saying, “a sign to make [it] known that there is power in the One who is sending you;” meaning, He has ability and control. This message was sent to Pharaoh, as the Chizkuni says, because “Pharaoh was haughty in his own eyes and called himself a crocodile, as it says, ‘O Pharaoh, king of Egypt, the great crocodile’ (Yechezkel 29:3). Hashem said to Moshe, ‘Go and tell Pharaoh, just as this staff turned into a crocodile and swallowed up staffs, and in the end turned back into a dried piece of wood, so to you swallowed up 12 staffs of the tribes of Israel and your end will be like a dry piece of wood, dead.” (Click here for Hebrew text.)
The Ibn Ezra in facts points out that Moshe’s staff turned into a snake for the Jews but a crocodile for Pharaoh in order to get this very message across to him. It would seem, according to the Chizkuni, that Hashem originally intended to show the 3 signs to Pharaoh as well, but something changed, a specific message had to be sent to Pharaoh, so only one sign was needed. What changed and why not give all 3 signs anyway; if one doesn’t work then maybe another one will get the message across? As the saying goes, “throw everything at him, including the kitchen sink, and maybe something will stick?!”
We must say that Hashem originally intended to give all three signs to Pharaoh through Moshe, as he did to the Jews in order to prove the authenticity of the messenger, Moshe. Although Pharaoh fancied himself as a god, and called himself the Great Crocodile of the Nile, the entire time he had the potential to reverse his opinion and acknowledge the supremacy of the Almighty Blessed Be He. Hashem gave Pharaoh a chance to the very end, right before Moshe confronted Pharaoh, to choose out of his own free choice to make that acknowledgement. But once Hashem saw Pharaoh was not going to realize this of his own free will, He told Moshe to show Pharaoh one wonder which had a specific message.
We see from here that when trying to get through to someone to teach them a lesson the best way is to pinpoint the exact issue and focus in on that, hitting the nail on the head, and hopefully the message will come across loud and clear. That’s better than throwing everything at him and hoping that something will stick.