The inspiration for the hassidic movement, Rabbi Yisrael Baal Shem Tov (c.1700-1760) – known by the acronym “Besht” – did not leave any complete written works. We have a few documents – some of them of questionable authenticity – that are attributed to him, yet by and large his legacy rests on collective memory, preserved in later writings.A precious document that has survived is a letter that the Besht penned to his brother-in-law, Rabbi Avraham Gershon of Kitov (d. 1761), who was living in the Land of Israel.The Besht gave the letter to his disciple, Rabbi Ya’acov Yosef Hakohen of Polonne (d. 1779), who planned to travel to the Holy Land. The letter was to be given to Gershon, in part as a recommendation for the bearer and a request that Gershon assist the new arrival.Alas, Ya’acov Yosef never made the journey and, sadly for Gershon, the letter never arrived at its intended destination.Fortunately for posterity, the letter remained in Ya’acov Yosef’s possession and was published 21 years after the Besht’s death, as an addendum to Ya’acov Yosef’s second book, Ben Porat Yosef (Korzec, 1781).The letter is particularly fascinating because it includes first-person descriptions of the Besht’s mystical experiences.On Rosh Hashana 1749 the Besht ascended the heavens and was privy to a heavenly decree that allowed a pogrom. The Besht asked for the pogrom to be replaced by a plague: better death by the hand of God than death at the hands of marauders. His request was granted. As the plague ravaged communities, the Besht gathered his circle of mystics in order to recite ketoret – the passage describing the incense offering in the Temple – in order to mystically combat the harsh decree. That night, the Besht had a vision where he was scolded: You asked for the plague, so you cannot now try to prevent it! The Besht continued the account in his letter to his brother-in-law: “And from then I did not recite ketoret, and I did not pray regarding this.”There was, however, one exception: “On Hoshana Raba alone, I went to the synagogue with the rest of the community, and by using a number of oaths because [I had] great fear, I recited ketoret one time so that the plague should not spread to our area.” The Besht reported that – with the help of God – he was successful at least on the local level.It is clear from this account that the ketoret passage has significant mystical valence. In truth, this was not the Besht’s innovation; rather, long-standing Jewish esoteric tradition recognized the potency of reciting ketoret.WHAT IS so special about ketoret? Why does the mysterious Temple incense seem to be more effective than any other ritual in combating harsh decrees? What is the secret of the ketoret? While this might be a question for those adept in Jewish esoteric rites, ketoret has a unique feature that can be appreciated by all.Temple ketoret was made from 11 ingredients, one of which was helbona (Exodus 30:34). The great 11th-century French commentator Rashi (1040-1105) identified helbona as galbanum; other authorities reached different conclusions regarding the identity of helbona. But all accept the sages’ declaration that helbona did not have a pleasant scent.Why include an item with a distasteful odor in Temple incense? Rashi explained that helbona was added to remind us not to hesitate as we consider whether to include sinners when we gather together to turn to God in prayer and supplication. Despite the helbona- like stench, sinners have a place in our communities.Indeed, it is easy to create a pleasant aroma from things that have an agreeable scent, just as it is easy to create righteous communities from righteous people. Helbona reminds us that the challenge is to take something that is pungent and, by mixing it with other ingredients, find its pleasantness. Our task is to stand with unsavory people, create a unified community, and produce a fragrant smell.This is perhaps the meaning of the words of the Ari – the great Safed kabbalist Rabbi Yitzhak Luria (1534-1572) – who taught that the secret of ketoret is that is sweetens harsh heavenly judgment. Ketoret is able to sweeten harsh decrees because that is exactly what the ketoret does: it sweetens the odor of helbona.This brings us back to the potency of the Besht’s magical ketoret recitation. Alongside its mystical valence, ketoret also has an accessible symbolism for those of us who are not steeped in Jewish esoteric tradition.What could be more potent than when the righteous recognize that even sinners are part of our communities? What could be sweeter than when we acknowledge that our task is to make our entire community fragrant – even those members who are not so pleasant? What could be more spiritually powerful than a declaration that we are a unified people? Perhaps we, too, can create spiritual perfume when we ensure that we make room for helbona-like people in our communities, and when we earnestly try to create a fragrant collective.The writer, a rabbi in Tzur Hadassah, is on the faculty of the Pardes Institute of Jewish Studies and a postdoctoral fellow at Ben-Gurion University of the Negev.