Sha'ar HaEmunah VeYesod HaChasidut, Introduction to Beit Yaakov 6

וכדאיתא בזה"ק (תרומה קס:) בענין כוונת שמע ישראל, דיחודא לבתר קא מיחד תלת סטרין ה' אלהינו ה' אחד למהוי כלא חד. ושם (קסא.) רבי חייא פתח אבתריה ואמר אתה הראת לדעת כי ה' הוא האלהים וכו' וידעת היום והשבת אל לבבך כי ה' הוא האלהים בשמים ממעל ועל הארץ מתחת אין עוד וכו' הכא תליא כל רזא דמהימנותא, למנדע מגו דא רזא דכל רזין סתימו דכל רזין סתימו דכל סתימין הוי"ה אלהים שם מלא וכלא חד. ובפרשת (פקודי רס.) ומאן דארכיב זינא בזיניה וידע לקשרא קשרא בקשריה היכלא בהיכליה דרגא בדרגיה, דא אית ליה חולקא בעלמא דאתי כמה דאוקימנא ועל דא האי איהו שלימו דכלא וכד אשתלים דא בדא ואיהו כלא חד עובדא זינא בזיניה דנפיק מהאי שלימו ההוא אקרי מעשה מרכבה, ורזא דא וייצר ה' אלהים את האדם שם מלא ואדם איהו עובדא דהאי מרכבה דארכיב דא בדא כדין ה' הוא האלהים וכו'. ועל זה איתא בזה"ק (תרומה קסא.) הנ"ל שזה הוא מצות וידעת היום והשבות אל לבבך כי ה' הוא האלהים בשמים ממעל ועל הארץ מתחת אין עוד: The Purpose of the Mystery of Faith
Having established that true knowledge is the knowledge of God’s revelation on earth, the author now shows how this to be the meaning of the Shema Yisrael prayer: “Hashem Elo-heinu, Hashem Echod.” That is, Hashem, the Transcendent God, is also Elo-heinu, the imminent God. In R. Gershon Henokh’s eyes, this defines the mystery of faith, for true faith is the ability to perceive God’s light and providence in each detail of creation. In the chapter following this one, R. Gershon Henokh refers to this knowledge as Ma’aseh HaMerkava, “the Workings of the Chariot.”⁴⁷In Hebrew, merkava is related to the word markiv, meaning “to join or assemble.” Thus, the “Work of the Chariot” means a perception of the union of God and creation. This was a term coined by the Sages of the Talmud in references to Yehezkel’s vision of a supernal throne, carried by angels, on which sat an image of the Divine. Talmudic mystics, who delved into the depths of this topic were known as “Descenders of the Chariot.” However, R. Gershon Henokh defines Ma’aseh HaMerkava in a novel way.⁴⁸In keeping with other teachings from the school of Izhitz. The merkava is not the chariot in Yehezkel’s, but the entirety of creation, which, when viewed through the lens of faith, becomes a dwelling place for the revelation of God in the world.
Concerning the meaning of the Shema Yisrael the Zohar writes (Terumah, 160b): The two words Shema Yisrael (Hear O Israel) express a unification of three sides, which are the three words Hashem Elo-heinu Hashem (Hashem is our God, Hashem), since it is all one. Further in the Zohar, it is written (Terumah, 161a): Rabbi Hiya spoke after him and said (Devarim 4:35), “It was shown to you, so you may know that Hashem is God, there is none other besides Him”; (Devarim 4:39) “And you shall know this day, and take into your heart, that Hashem is God, in the heavens above and on the earth below, there is none other.” The entire mystery of faith depends on these words. From this one can know the secret of all secrets, the most hidden of all mysteries, which is that “Hashem Elo-him,” is one full name, and it is all one. And in the Zohar (Pekudei, 260a): One who knows how to combine similar things (min b’mino) – to make connections, connecting chamber to chamber, level to level⁴⁹Meaning, he possesses the wisdom necessary to unite the effect with its cause. In this way, he unifies this world with the upper worlds. – has a share in the world-to-come, as we have established. Therefore, it is the completeness of all. And when the levels are completed, one joined to the other, then it is all one action, and the completeness that comes out of this combination (min b’mino) is called Ma’aseh Merkava,⁵⁰The root of the word, “to assemble, to combine” (הרכבה)and the word for chariot (מרכבה) is the same. the workings of the Divine Chariot. This is the secret of (Bereshit, 2:7), “and Hashem Elo-him formed man.” “Hashem Elo-him” is one complete name, and the resulting action of combining the two names into one is the formation of man. In this way we say, “Hashem is Elo-him.” This is as the Zohar states above, that the mystery of fatih is found in the commandment: “And you shall know this day, and take into your heart, that Hashem is God (which is the same as saying Hashem is Elo-him), in the heavens above and on the earth below, there is none other.”