The ten plagues reiterated during the Seder are the ten plagues that God inflicted on the Egyptians in order to free His people, the Israelites. They are:

1. Blood - דם

2. Frogs - צפרדע

3. Lice - כנים

4. Beasts - ערוב

5. Blight - דבר

6. Boils - שחין

7. Hail - ברד

8. Locusts - ארבה

9. Darkness - חשך

10. Slaying of the firstborn - מכת בכרות

      The ten plagues may be categorized according to two classifications – severity and division. By severity we mean that each subsequent plague was more severe than its predecessor. By division, we mean that certain plagues inflicted only certain individuals. The blood, frogs, and lice affected everyone in Egypt whether Egyptian or Israelite; however, the rest of the plagues were directed strictly at the Egyptians while the Israelites remained immune. The exception of course was the last plague which was potentially aimed at everyone although more particularly the Egyptians since they were not told by a prophet what they could do to avoid the loss of their firstborn. What distinguishes the tenth plague from all others was that it was inflicted only on those who did not exercise faith in the living God and obey His command to kill the Paschal lamb and spread its blood on the doorposts and lintel. Also, God carried it out personally; it was not the work of Moses, His servant.

      This last point is of supreme significance because it shows the Jews that God Himself delivered them. It also demonstrates God’s superior power over the gods of the Egyptians, including the supposed deity of Pharaoh and his household. In this vein, it is interesting to note that each plague was directed at the various elements that the Egyptians worshipped. For example, the first plague turned the Nile into blood. The Egyptians completely depended on the Nile and therefore worshipped it as their divine provider. By having Moses turn it to blood, God showed that He had power over that which the Egyptians worshipped.

      While this must have been impressive, it could not have been nearly so impressive on Pharaoh’s mind and conscience as was the last plague, which really struck home (pardon the pun). According to Egyptian theology, each Pharaoh contained something divine. Perhaps he was thought of as a god, perhaps as a son of god, perhaps simply as a divinely chosen being who would become a god. Either way, he was looked on as some type of deity. Because his eldest son would one day inherit the throne, he would also have been viewed as being divine, or at least divinely preferred. By killing this son, God showed Pharaoh that He had total power, that regardless of whether the deities Pharaoh worshipped were actual, there was no mistaking that God was more powerful, that He was King of kings. Therefore, in the executing of the ten plagues, and in the ultimate deliverance of Israel from Pharaoh’s servitude, God scored a complete victory, showing that without a doubt He had all power for deliverance. It was therefore the house of Israel’s divine obligation to worship Him as the only true and living God, and to shun the idolatry of their former masters, the Egyptians. The reciting of the ten plagues reminds Jews of their still current obligation in this matter.

      In order to help Jews remember the ten names of the ten plagues, Rabbi Judah recommended three mnemonic words composed of the first Hebrew letter of each plague. However, this was not the only reason that Rabbi Judah created these mnemonics. As Solomon Zeitlin[1] points out, Psalm 78 mentions only seven plagues, Psalm 105 eight, and in both cases the order is different than in the Torah. Moreover, the Book of Jubilees mentions all ten plagues but also in a different order than what is found in Exodus. By establishing the mnemonics, Rabbi Judah helped avoid potential confusion over the true order of the plagues that may have been introduced by these differing accounts.

      Following is another explanation whereby you can establish that the total number of plagues add up to exactly ten; by counting each of the first three two-word phrases and the plural forms of each of the last two words, as follows:

With a mighty hand indicates two; and with an outstretched arm, two; and with great terror, two; and with signs, two; and with wonders, two.

[1] Jewish Quarterly Review (38, 1948) 455