The midrash taught that the arba minim — the four species shaken on the festival of Sukkot — are not a random bouquet. Each one maps to a part of the human body, so that when a Jew lifts them together he offers himself whole to God.
The lulav, the palm branch, is tall and straight, rising in front of the chest where the heart beats. It teaches that we should serve God with the entire body, not in fragments. The hadas, the myrtle, has leaves shaped like the human eye — for the eye recognizes the deeds of others and can also turn to the Torah and gather knowledge of the law.
The aravah, the willow leaf, is shaped like the lips, with which a human being praises and thanks the Eternal. The etrog, the citron, is shaped like the heart, the organ of devotion. The sages added that the myrtle is mentioned before the willow in Scripture because we see a thing before we name it — the eye precedes the lips, and the mind precedes the confession.
Heart, eye, lip, spine — four parts of the human frame, lifted in one bundle. David sang it first (Psalm 35:10): All my bones shall say, O Lord, who is like unto Thee? The midrash on Sukkot takes David's line and turns it into choreography. The worshiper does not hold a liturgy. He becomes one.