After the period of bein ha'metzarim, the three weeks of "retributions" in which we mourn the destruction of the Temples, there ensue seven weeks of "consolations" until Rosh HaShanah, of the New Year. The Shabbat after Tisha B'av--the first of the "consolations"--is called Shabbat Nachmu, the "Shabbat of Consolation," as per the opening verse of the Haftara: "'Comfort, comfort my people,' says your G-d" (Isaiah 40:1).
We note that the prophet voices a double consolation: "comfort, comfort my people?." The Sages explain that just as Israel carried out a "two-fold sin" ("Jerusalem has sinned a sin" Lamentations 1:8), and were requited with a "two-fold punishment" ("For she has received double for all her sins from the hand of G-d"--Isaiah 40:2), so too they are consoled in a "two-fold" fashion ("'Comfort, comfort my people,' says your G-d").
Furthermore the Sages state that just as Israel sinned with the word yesh--denoting "something" with independent existence ("Is G-d here [present] amongst us or not"--Exodus 17:7), and were smitten with the word yesh ("Does there exist any pain like my pain?"--Lamentations 1:12), so too they are consoled with the word yesh (" I have what to bequeath [to] those who love Me, and I shall fill their storehouses"--Proverbs 8:21).
On the verse in Job (11:6): "He would relate to you hidden recesses of wisdom, for His salvation is two-fold; and know that G-d exacts from you less than your iniquity deserves," the Sages explain that G-d consoled Moses after he broke the first tablets containing the Ten Commandments. G-d said to Moses as follows:
Don't feel pained about the first tablets that contained no more than the Ten Commandments, for the second set of tablets that I give you will have in them collections of laws, homiletical interpretations and legends. Thus it is written: "He would relate to you hidden recesses of wisdom for His salvation is two-fold." Moreover, you now receive the good tidings that I have forgiven you for your mistake (breaking the tablets), as it says, "and know that G-d exacts from you less than your iniquity deserves."
The tablets were broken on the 17th of Tamuz, the first day of the three weeks of retribution. The aforementioned consolation of Moses is connected with the Torah portion of Va'etchanon, in which the Ten Commandments appear for the second time in the Torah--"For His salvation is two-fold." The portion of Va'etchanon is always read on the "Shabbat of Consolation," the first of the seven weeks of consolation.
In the verse just discussed, the words for "salvation" (tushiya) and "exacts" (ya'she) reflect a play on words. The word tushiya connotes two contradictory understandings: yeshut meaning vigorous strength and tashut meaning weakness and forgetfulness, as explained by the commentators. Accordingly, the phrase "two-fold salvation" hints to both the sin--they sinned with yesh and in a "two-fold" manner, and also to the rectification and consolation--they are consoled with yeshand also in a "two-fold" fashion.
The Work of Repentence
In Chassidut it is explained that with reference to spiritual work and growth, the "double salvation" is the process of repentance. Note what the founder of Chabad Chassidut, Rabbi Shneur Zalman of Liadi writes in his Epistle on Repentance (Chapter 9):
In Tanna Dvei Eliyahu we find, "A man commits a sin and is liable to death before the Almighty. What shall he do and live? If he was accustomed to studying one page, he shall study two, to studying one chapter, he shall study two chapters?." This parallels the illustration of the cord severed and then re-knotted--the place of the knot is so much thicker than the unaffected portion. So it is with the "cord" of His possession (Israel)."
When a person sins it is because he feels he is a "something," distinct and removed from G-d who has created him and who enlivens and sustains him, each and every second. This sense of separate existence is called in the Holy Zohar, "the strength of the body" which indicates that there is a "weakness of the soul." The process of rectification therefore entails the nullification of the ego sense of being a "something," which is the "weakness of the body." The sincere efforts made to nullify the consciousness of ego as an entity distinct and removed from G-d will, in and of itself, automatically heighten the power of the soul to cleave to G-d, reflecting the state of "strength of the soul."
However, this is not the ultimate object of the process of repentance. Rather, the ultimate aim of repentance is to achieve the level of consciousness of the "True Something." By cleaving to G-d and His Torah, the created something reflects by himself the essence of G-d, (the word for "essence" in Hebrew is related to the word for "strength"), the only "True Something." In this state one has "strength of soul" and "strength of body" at one and the same time--since the body has been completely purified and rectified.
This is the deep, inner meaning of "comfort, comfort my people." First, "comfort" through nullification of the ego, is "separate something," to the Divine "nothingness" that enables one's existence. Secondly, "comfort" by transforming the human being, the "created something" to a level where one truly reflects Divinity, the only "True Something."
Consolation--The Transformation of Thought
The word nechama (comfort, consolation) connotes a "change in one's thinking" from one pole to its opposite (or as the Radak puts it: "this is the idea of remorse"). We find that G-d--wishing to resemble the human being that He created in His own image--changes His attitude from favorable to unfavorable ("and G-d regretted that He had made man"--Genesis 5:6) and from unfavorable to favorable ("And G-d regretted the evil which He thought to do to His people"--Exodus 32:14). We also find that G-d who is "not--man"--does not, even in the slightest, show remorse or regret ("And also the Eternal One of Israel will not lie--not change His mind; for he is not a man, that He should change His mind"--1 Samuel, 15:29).
After the descent "from the zenith to the nadir" of Tisha B'av, there must necessarily be a change of direction, a change of "mindset." We have reached the lowest point possible; there is nowhere to go but up--"a descent in order to ascend." The new mindset, as opposed to the previous one, revolves around the understanding that the whole purpose of the descent was just in order to ascend. The descent itself is part and parcel of the process of spiritual growth and advancement.
This understanding is just one "consolation," one answer to the question, "Why do we have to experience Tisha B'av?" However, "one should be in a state of repentance throughout one's life" (Talmud Bavli, Shabbat 153a). Each day one must do teshuvah ("repent," in Hebrew similar to the word for "answer") for yesterday's relatively lower level of Divine awareness and service from the new heightened consciousness of Divinity.
How are we then to understand the second level of "consolation" in comparison to the first one? The first "consolation" is that "the descent was for the purpose of ascending." However, the second, more profound "consolation" is--as opposed to the first understanding--"that the ascent was just for the purpose of descending!" This means that the ultimate intention of creation is not that the person progress to a state of complete self-nullification, to the point of losing one's physical existence (as occurred to Ben Azai in the story of "the four who entered the orchard [paradise]" in Talmud Bavli, Chagiga 14b). Rather, the ultimate purpose is "to create a dwelling place for G-d in this lower, material plane" (Midrash Tanchuma, Nasso 7), to reveal G-d's essence in the very physicality of this world.
Thus, the two "consolations"--"the two-fold comforting"--are indeed two distinct levels in the rectification of material existence--"a two-fold salvation." First is the nullification of physical existence to a state of "nothingness." Then follows the purification of the "created something" (physicality, materiality) to reflect the "True Something," namely the Holy One, Blessed be He.