126. The "greater luminary" is the sun, which has twelve openings and twelve hours, as the sun rules over the day. The "lesser luminary" is the moon, which also has twelve openings, the moon rules over the night, which has twelve hours. For this reason, IT IS WRITTEN: "On that day Hashem shall be one, and His Name One" (Zecharyah 14:9). "ONE" IS MENTIONED TWICE: ONCE FOR YUD HEI VAV HEI, WHO IS ZEIR ANPIN, "THE GREATER LUMINARY," AND ONCE OF HIS NAME, WHICH IS THE FEMALE, "THE LESSER LUMINARY." The sun together with its twelve openings becomes the thirteen attributes of Mercy. The moon together with its twelve openings also adds up to thirteen. SO THE SUN BECOMES ONE AND THE MOON BECOMES ONE; THEN IT SAYS, "HASHEM SHALL BE ONE, AND HIS NAME ONE," BECAUSE THE NUMERICAL VALUE OF ECHAD (ONE) ADDS UP TO THIRTEEN. Thus, the sun and the moon become one and the day and night also become one. This is why it is written: "And there was evening and there was morning, one day" (Beresheet 1:5). The secret OF THIS UNION is ONLY applicable on high.
138. In the beginning, THE LETTER Aleph, which is the beginning and end of all the grades, WAS INSCRIBED. Although it is the imprint on which the upper and lower grades were imprinted, it is still referred to in the singular as Echad (one), WHICH MEANS THAT THE ALEPH IS ONE IN NUMERICAL VALUE. IT TEACHES US that, although it contains many forms AND INCLUDES ALL THE GRADES, it remains only one. THUS, ALL THE GRADES ARE AS ONE IN IT. Assuredly, THE LETTER Aleph is the letter upon which the upper and the lower beings depend.