On Sukkot, we hold together four diverse forms of life and make a blessing. If one is missing—no mitzvah, no blessing.
One is the Lulav—a date-palm frond. The taste of the date represents the taste of Torah study. The Lulav represents those whose lives are filled with Torah study.
Another is the Hadas—a myrtle branch. The myrtle’s pleasant aroma pleases all around, just as one whose life is filled with mitzvahs is appreciated by all wherever he goes.
Another is the Etrog—a citron fruit. It has both taste and a beautiful aroma. Some people divide their life project between studying Torah and doing mitzvahs—emphasizing the harmony of the two, but not managing to excel in either.
And then there is the Aravah—a humble willow branch. No taste. No aroma.
Why do we need an Aravah to do a mitzvah? To make a blessing?
Because the Aravah is simple. If something needs to be done, the Aravah is there to do it. Because that’s what its Creator wants of it.
That’s something we all need—vitally. Crucially. Simplicity.
During the seven days of sukkot we present our seven qualities of our soul for correction. Each quality or characteristic forms the soul structure, a vessel to be filled with G_d's Light.
Three characters are represented by the myrtle leaf, another two properties by the willow branches, another level of characteristics by the palm fronds and the last by the citron or 'etrog'.
These properties of the soul or 'sefirot' are layered on 7 levels of spiritual ascent. So 7 lights or 'guests' enter us to correct each level. Each character becomes corrected with theses lights of Hassdadim found in qualities of love, friendship, partnership, compassion and mercy. Then these cottected properties are prepared to be connected together to form our soul.