There is a love of God that surpasses all the forms of love the Tanya has described so far. Rabbi Schneur Zalman of Liadi compares it to gold surpassing silver. It burns like fiery coals.
The previous forms of love emerge from the right side of the divine, from chesed (חסד), lovingkindness. They are characterized by longing, by yearning to draw close. The Hebrew word kesef (כסף), silver, shares a root with the word for longing, as in "you longed for your father's house" (Genesis 31:30). But this higher love comes from the left side, from gevurah (גבורה), the divine attribute of strength, rooted in binah (Understanding) ila'ah (בינה עילאה), supernal understanding.
When a person contemplates the greatness of the Ein Sof (אין סוף), before whom everything is truly as nothing, the soul catches fire. It does not merely yearn to draw close. It surges upward, striving to leave the body entirely, like a flame leaping off a wick, desperate to be parted from the wood that holds it down. First comes thirst: "My soul thirsts for You" (Psalms 63:2). Then lovesickness (Song of Songs 2:5). Then the rapture of complete soul-expiry: "My soul pines away" (Psalms 84:3).
This is the spiritual root of the Levites, whose Temple service was to raise their voices in melody and thanksgiving. Their song embodied ratzo va-shov (רצוא ושוב), the ecstatic "advance and retreat" of the soul, rushing toward God and pulling back to remain in the body, like the angels described by Ezekiel, whose movement is "like the appearance of a flash of lightning" (Ezekiel 1:14).
The Tanya admits it cannot fully explain this love in writing. But it promises that every person of warm heart and deep intelligence who binds their contemplation to God will discover it hidden within their own soul, each according to their capacity.
All the distinctions and gradations of love, that have been mentioned above, derive from the “right side,” from the distinction of “priest, man of grace”1 Zohar I:256b; 258b. and are called kesef hakodoshim (“longing for holy things”)2 כסף הקדשים—lit. “holy silver” (cf. II Kings 12:5). etymologically, as in “For you longed repeatedly3 נכסף נכספת—from the same root as כסף. for your father’s house.”4 Genesis 31:30. There is, however, yet another distinction of love which excels them all, as gold is superior to silver, and this is a love like fiery coals from the distinction of the supernal gevurot from binah ilaah (supernal understanding).5 Chochmah and binah in the intellect have their counterparts chesed and gevurah in the middot. This is when, through contemplation on the greatness of the En Sof, blessed is He, before Whom everything is truly accounted as nought, the soul is kindled and flares up toward the glory of the splendor of His greatness in order to gaze on the glory of the King, like glowing coals of a mighty flame which surges upward, striving to be parted from the wick and the wood on which it has taken hold. This is brought on by the preponderance of the element of Divine fire that is in the divine soul. In consequence of this it develops a thirst, as is written, “My soul thirsts for You”;6 Psalms 63:2. next it attains the distinction of “lovesickness”;7 Song of Songs 2:5. and then it reaches a state of very rapture of the soul (כלות הנפש) as is written, “Indeed, my soul pines.”8 Psalms 84:3. From here [supernal gevurot] issues forth the root of the Levites9 Whereas the priest is the man of chesed, the Levite symbolizes gevurah, as explained in many sources of Kabbalah and Chasidut. Cf. e.g., Likkutei Torah, Bamidbar 1c; Korach 54a f; Va’etchanan 8b. [on earth] below [and in the World to Come, when the world will be exalted, they will become the priests, as the Arizal10 See above, ch. 2, note 9. commented on the verse, “But the priests, the Levites,”11 Ezekiel 44:15. that the Levites of today will become the priests of the future]. The service of the Levites was to raise the voice of melody and thanksgiving, with song and music, with tunefulness and harmony, in a manner of “advance and retreat”12 The counterpart of the ecstatic worship by the angels (Chayot); cf. Ezekiel 1:14. which is the distinction of the intense love resembling the flame that flashes out of the lightning, as is mentioned in the Gemara [Chagigah, ch. 2].13 Chagigah 13b. It is impossible to elucidate this matter clearly in writing. Yet every warmhearted and intelligent person gifted with understanding, who deeply binds his mind and contemplation to G–d, will discover the goodness and light which are treasured up in his intelligent soul, each according to his capacity—[“there is one who is affected [in one way]…and there is one who is affected [in another], and so forth”]—prefacing it with the fear of sin, in order to be completely parted from evil, that the iniquities may not interpose…, G–d forbid. The order of the service in occupying oneself with the Torah and commandments, a service derived from the category of the said intense love, is in the manner of “retreat” alone, as is written in Sefer Yetzirah, “And if your heart hastens, return to the One.”14 1:8. Cf. Tikkunei Zohar, Introduction 7a. The interpretation of [the phrase] “if your heart hastens” is the craving of the soul that is in the right side of the heart —when it gains sway15 …over the left part, i.e., over the natural desires of the animal soul. and bursts into flame and grows so exceedingly enraptured that the very soul is consumed with a desire to pour itself out into the embrace of its Father, the Life of life, blessed is He, and to leave its confinement in the corporeal, physical body, in order to attach itself to Him, blessed be He—then one must take to heart the teaching of the Rabbis, of blessed memory, that “against your will you live”16 Avot 4:22. in this body, animating it for the purpose of drawing downward the higher life from the Life of life, blessed is He, through the life-giving Torah, that there may be a dwelling in the lower world for His Oneness, blessed be He, in a revealed state. As has been explained above, and as is explained in the holy Zohar,17 II:135a. “that there be ‘One in One,’ the meaning of which is that the yichud hane’elam (hidden Unity) shall become a category of the ‘revealed world.’” And this is the interpretation of the text, “Come, my beloved….”18 “…let us go out into the field…” (Song of Songs 7:12), alluding to the consummation of love in the “field,” i.e., this material world. Or perhaps it refers to the well-known Shabbat hymn, “Come my Beloved to meet the Bride.” From this will be understood the adage of the Rabbis, “against your will you live; against your will….”19 Avot 4:22. What then should one’s desire be? The answer will be found elsewhere20 See Torah Or 2a; 25b, et al. in the lengthy explanation of this Mishnah, “against your will you live”—with the aid of the Life of life, blessed is He.