The main mitzvah we have during Sukkot is the taking of the 4 species (arba minim): etrog, lulav, three hadassim and two aravot. We have to take all 4 species and bind them together to show that although each kind represents a different type of jew, the mitzvah of Sukkot unites us all. The lulav has taste but no smell, symbolizing those who study Torah but do not possess good deeds. The hadass has good smell but no taste, symbolizing those who possess good deeds but do not study Torah. The aravah has neither taste nor smell, symbolizing those who lack both Torah and good deeds. The etrog has both good taste and good smell, symbolizing those who have both Torah and good deeds.

Another explanation finds the lulav and etrog set alluding to different parts of the human body. Each of the species or its leaves is similar in shape to the following organs: Lulav; the spine, Hadass; the eye, Aravah; the mouth, Etrog; the heart. By binding them together for a mitzvah, the Jew shows his desire to consecrate his entire being to the service of God.