The Music of Halacha: Succot: The Symbols of God & Israel
The Likutei Maharich maintains that despite all the midrashic and kabalistic explanations of the symbolism of the four species, they remain one of the sublime mysteries of the Torah.
Rabbi Moshe Eisemann of Yeshivas Ner Yisrael explains that we must still have a basic understanding of the species, what they represent, and, most of all, why we are enjoined to fulfill this specific mitzvah with extra joy. He has a magnificent and practical explanation of the four species and the joy that they bring.
Each of the four species represents a different type of Jew. The Lulav, which is from a date palm, has taste, but no smell. This represents the Jew who has learning, but lacks the fragrance of good deeds. The Hadas, myrtle branch, has a wonderful fragrance but no taste. This hints to the person who has good deeds but no knowledge. The willow has neither taste not fragrance. This is the Jew who has neither good deeds, nor learning. The esrog has both a wonderful smell and good taste, corresponding to the person who has both good deeds and great knowledge.
The four species also represent different attributes of God. (See Vayikra Rabbah 30:9)
The Four Species represent the Patriarchs and Matriarchs, (ibid.10), and the teachers of Israel.
The four species represent God and us, the Jewish people. When we shake our Lulav we are celebrating the relationship we share with the Almighty. We hold in our hands the symbols of God and Israel. That is the source of our joy.