The sheep [and goat] is saying: "Who is like You among the might ones, G-d, who is like You, mighty in holiness, awesome in praise, worker of wonders." (Exodus 15:11)
Rabbi Yishmael would say: Be yielding to a leader, affable to the black-haired, and receive every man with joy.
Hod shebeNetzach (glory and gratefulness within the context of victory and endurance)
In the twenty-sixth week, that of Rosh Chodesh Nissan, in Perek Shirah, the small pure (kosher) domestic animal proclaims that no one is as strong, awesome and miraculous as Hashem (Exodus 15:11). The small pure domestic animal is a reference to the sheep (the month of Nissan corresponds to the zodiac sign of Aries), as well as to the goat. Rosh Chodesh Nissan marks the inauguration of the Mishkan, the Tabernacle, in which sacrifices of pure kosher animals, such as the sheep and goat, were brought.
Nissan is the month of redemption and miracles. The relationship of shepherd and flock is one of the most important metaphors for the relationship between G-d and the Jewish people. G-d is far above our comprehension, just as the shepherd is also completely beyond the understanding of his flock. At the same time, like sheep, we have total humility and faith that our Shepherd will lead us in the right path, despite perhaps having to face foxes and lions along the way.
The goat is also used a symbol for the Jewish People in the famous song that is sung by many Jews on Passover night, Chad Gadya. The song’s name means “One Goat,” and also appears to be phonetically similar to the word Haggadah, the text that is read during the Passover Seder. Chad Gadya is similar to Perek Shirah, in that it also includes many animals and natural elements. The animals in Chad Gadya function primarily as symbols for various exiles we have endured and the different nations that conquered the Land of Israel. The cat that eats the goat is a reference to Assyrians; the dog that eats the cat is a reference to Babylon; the stick is Persia; the fire is Macedonia; the water, Rome; the ox, the Saracens; the slaughterer, the crusaders; the Angel of Death, the Turks. At the end, G-d saves us from all these enemies and returns us to our Land. The two zuzim, the coins used to purchase the goat are said to be a reference to the two tablets containing the Ten Commandments given to Moses at Mount Sinai, but also appear to be a reference to the two Temples that were destroyed, and its people exiled. Zuz means to move, to change places. The Third Temple, however, will not move, it will be everlasting.
Similarly, each animal in Perek Shirah that sings during Nissan represents a different exile, as well as a redemption from it. Sheep were G-ds to the Egyptians, our first exile, and the goat, Seir in Hebrew, is a reference to Esau, our last. It was in this month that we were redeemed from Egypt, and it is in this month that we will be redeemed in the future.
The Torah states unequivocally that Nissan is the head of all months, Rosh Chodashim. It is therefore represented by the Tribe of Judah, who was the leader of his brothers, and from whom King David descends. All legitimate kings of the Jewish people - including Mashiach – are descendants of King David and therefore of Judah. The word for Judah in Hebrew, Yehudah, comes from the word hoda’ah, which means acknowledgement. This is the same root of the word Modeh, as in the prayer we make when we first get up in the morning, the Modeh Ani, in which we acknowledge G-d as our King and thank Him for returning our soul. The tribe of Judah is characterized by self-sacrifice, acknowledgement, and thankfulness.
Because the Egyptians idolized sheep, it is extremely appropriate that it be the one to proclaim the absolute greatness of Hashem. The Sheep is the animal used in the Passover sacrifice, showing the Egyptians that G-d is far greater than any other god. On Shabat HaGadol (the “Great Shabbat,” which takes place right before Passover), we celebrate the miracle of how the Egyptians did not react negatively toward the Jewish people, when they tied sheep to their bedposts, and told the Egyptians that they were about to sacrifice their gods in the coming days.
Nissan is the month of Passover, and it is therefore appropriate that this week’s song be from the Song of the Sea, which was sung after the miracle of the splitting of the Sea of Reeds.
The number twenty-six is the gematria of G-d’s name, “Hashem.” Twenty-six also equals two times the number thirteen, the gematria of the word echad, one, as well as ahavah, love.
Rabbi Yishmael in Pirkei Avot teaches us this week that we must submit to a superior (literally “the head”), and be courteous to a younger person, greeting every person with joy (III:12). Among the kohanim, Rabbi Yishmael was the head, the Kohen Gadol. In addition to his close connection with Hashem, Rabbi Yishmael, as Aaron before him, had a great love for each member of the Jewish people, independent of his or her status or stature. This verse also has a clear connection with Nissan, the head of the months.
The sefirot combination for this week results in hod shebenetzach. With humility and gratitude, self-sacrifice and acknowledgement, we achieve the miraculous victory and redemption that takes place during this month.
We learn from the sheep and the goat that our work of improving ourselves physically and spiritually must be based on our strong belief that only Hashem can truly redeem us.
 While Rabbi Slifkin translates this animal only as sheep, Rabbi Lazer Brody includes goats as well. The Hebrew term can be translated literally as “small/thin pure animal.”
 Wikipedia, available at: http://en.wikipedia.org/wiki/Chad_Gadya
 Exodus 13:16