Our sages interpret the verse (Psalms 35:10), "All my bones [i.e., my entire being] shall say O' God, who is like You?'" to refer to the four species of the holiday of Sukkot, each of which resembles a part of the human body, all of which together praise God–"who is like You?" (VaYikra Rabbah 30:14; Midrash Tanchuma, Emor 19):
The lulav, whose central pillar is referred to as its "backbone" (shidrah) resembles the backbone of man.
The leaves of the myrtle branch (hadas) resemble the eyes of man.
The leaves of the willow branch (aravah) resemble the lips of man.
The etrog resembles the heart of man.
The phrase "O God, who is like You?" equals in gematria 162, which equals the word b'tzelem ("in the image of"), which appears in the beginning of the Torah in the phrase "in the image of God He created him [man]." The entire phrase "in the image of God" (b'tzelem Elokim) equals 248, the number of limbs in the human body (according to the Mishnah, the number of bones in the human skeleton) which correspond to the number of positive commandments of the Torah, and numerically equal the name of the first Jew, Abraham.
Let us meditate on the four major limbs which correspond to the four species of Sukkot, in accordance with the general principle of Kabbalah and Chassidut that all of the elements of the spiritual service of the High Holidays which precede Sukkot, find their material manifestation in the physical mitzvot of the festival of Sukkot.
When we bless and praise God with the four physical species (with "all my bones") and shake them in all directions to reveal God's kingdom in all aspects of reality, we reflect, on the physical plane, the spiritual devotion of our heartfelt prayers to God on Rosh HaShanah (the day that we crown God [i.e., arouse Him, as it were, to desire] to be King) and Yom Kippur (the day that we, as a people, rise to the level of becoming the sole agents of God to reveal His kingdom on earth).
Of prayer, in general, it is said, "The supplicant should direct his eyes downward but his heart upward" (Yevamot 105b). At the beginning of the silent devotion, with backbone erect (and when bowing, all of its vertebrae opened in true "bitul" and inaudible song to God), we say: "L-rd, open my lips, and my mouth will utter Your praise" (Psalms 51:17. The Kabbalistic interpretation of this verse is central to the kavanot [mystical meditations] of Rosh HaShanah.).
Thus we see that it is these four major limbs specifically which participate in the Divine service of prayer.
At an even deeper level of awareness, the heart (the etrog) directed in prayer upward, encapsulates the consciousness of "to Whom am I praying?" The eyes (the myrtle leaves), directed downward (toward reality) encapsulate the consciousness of "what am I praying for?" The moving lips (the willow leaves) of prayer encapsulate the consciousness of "who, in fact, is praying (myself or God Himself)?" The backbone (the lulav) of the one standing in silent devotion encapsulates the consciousness of his upright state of trust and determination that "my prayer will surely be answered."
The first three states of consciousness are expressed as questions. In the service of prayer itself, the questions become resolved, their answers become clear: "I am praying to God A-lmighty, the Creator and all-encompassing Essence of creation"; "I am praying for the redemption of the world with the coming of Moshiach, at the collective as well as personal level"; "It is by the power and grace of God that my lips and mouth open to praise Him."
The fourth state of consciousness, which in the order of the Midrash, is in fact the first, the backbone of all consciousness, is initially expressed as an affirmation. Before one stands in prayer, he must be sure that his prayer will indeed be answered. This is the continual state of consciousness of the Jew, existentially connected to God A-lmighty, which motivates and spiritually empowers him to fulfill the exhortation of our sages, "Would that one would pray the whole day long" (Berachot 21a, etc.).
The lulav stands higher than all the other species, for which reason we pronounce the blessing of all the species over it ("Blessed be You…who has…commanded us to lift up the lulav"). In particular, the lulav expresses the exclamation of victory ("our side has won") of the spiritual battle that took place over the period of the High holidays.
We may derive yet another profound realization from the above meditation. The myrtle and willow branches are bound to the lulav and lifted up together with it by the right hand. The etrog is lifted by the left hand and thereafter brought together to the three species on the right.
As explained above, the etrog represents the aspiration of the heart to "reach" God Himself. Were this aspiration to express itself without bound, it would result in the soul leaving the confines of the body (just as in the case of Nadavand Avihu, the sons of Aaron, who experienced "run" without the ability to "return"). The left is the controlling force that does not allow the "run" of the soul to reach this negative extreme. Of the left hand it is said: "the left hand pushes away" (where as "the right draws close") (Sotah 47a). This means that the left does not allow for the soul and God to totally merge (as before creation) and become absolutely one. In this world, the "run" of the soul must remain penultimate ("always approaching but never reaching the limit," Berachot 26b).
For this very reason, God created man with his heart on his left. Slowly (but surely) the left lifts up the etrog and connects it to the species on the right. Only then is the mitzvah performed. The upward "run" of the etrog to the left inspires the downward "return" of the species to the right.
Thus we conclude that the backbone of Divine service is represented by the upright lulav on the right, whereas the essence of heartfelt prayer itself is represented by the etrog, the heart, to the left. And so do our sages say, "the All-merciful One desires the heart" (Sanhedrin 106b). The All-merciful One desires that heart which (most) desires Him.
All of the four names of the species–etrog, aravah, lulav, hadas–add to equal 1024, which equals 32 squared. 32 = "lev," "heart." Thus, altogether, they express the perfect heart (a square number reflects the perfected state of its root). Remarkably, the three words for backbone (shidrah), eye (ayin), and lip (safah) also add to equal 1024, the perfected heart. Together with the fourth word, heart itself (lev), all four limbs ("all my bones") equal 1056, the "diamond"-form of 32, the double "triangle" of 32!
Let us end in prayer: "Purify our hearts to serve You in truth," that we merit to the great joy of the festival of Sukkot with the revelation of Moshiach (whose name permutes to spell "He shall be joyful" and "He shall make joyful") and the complete redemption of Israel and the entire world ("my entire being"), Amen.