The incense offering (), a blend of aromatic substances that exhale perfume during combustion, usually consisting of spices and gums burnt as an act of worship, occupied a prominent position in the sacrificial legislation of the ancient Hebrews.The Jewish Encyclopedia, vol. VI, Funk and Wagnalls Company: New York 1904, p. 568

The correct blend of sweet spices and aromatic condiments used in making the incense offering was a carefully guarded secret at the time of its offering, fully known only by the compounders of the incense offering to prevent its replication in the worship of foreign gods. The priests of the House of Avtinas, who were charged with preparing the incense during the Second Temple period, kept the technique and exact proportions secret, for which the rabbis rebuked them according to the Mishnah, Yoma 3:11. "The craftsmen of the House of Avtinas did not want to teach the secret of the preparation of the incense. [....] about these who were concerned only for themselves it is stated: “But the name of the wicked shall rot” (Proverbs 10:7)."

Today, what is known of the incense offering has been carefully gleaned from Jewish oral traditions. Various conflicting opinions in Jewish classical writings have also filtered down as to its proper composition. Modern scientific research conducted in the last century has shed considerable light on these findings.

General overview

Use in antiquity The priests of Aaron's lineage were entrusted with the duty of burning incense in the Temple sanctuary. This was done upon a golden altar laid up within the outer chamber of the inviolable house. Those who were not of the priestly stock were prohibited by law from compounding incense in the same manner in which it was compounded by those of Aaron's lineage. Anyone attempting to do so with the intent of indulging his olfactory senses committed thereby a sacrilege and was made liable on that account to extirpation.Exodus 39:38; Mishnah (1977), s.v. Kareithoth 1:1, pp. 562–563 However, to compound incense in order to instruct others was permitted, or to burn incense by making use of part of the same components, especially to impart its smell unto clothing, or simply to enhance the ambiance of one's house, this was permitted in Judaism.

During the late Bronze Age, the duty of burning incense was performed by the priests in the Tent of Convocation throughout their journeys in the wilderness while en route to the Land of Canaan. This practice continued all throughout the nascent years of Israel's settlement in the land, when the Tent was pitched in Gilgal, and in Shiloh, and in Nob and in Gibeon, and they did so in the Temple which was built by King Solomon in Jerusalem, and later in the Temple built by the returning exiles. The priests would offer this incense offertory twice a day; once, in the morning, immediately after clearing the stone altar of its coals and which remained after the daily morning whole-burnt offering, at which time, some of the coals were laid up upon the altar of incense.Mishnah Yoma 3:5; cf. Commentary of Rabbi Obadiah da Bertinoro, Mishnah Tamid, ch. 2, passim; "Sefer ha-Chinukh," mitzvah # 103. The Mishnah in Yoma 3:5 says that the time of the morning incense was between the tossing of the blood and the burning of the animal's limbs. Again, towards the evening, after clearing the altar from its coals and embers, some were put upon the altar of incense within the antechamber of that sacred house.Rabbi Obadiah da Bertinoro, ibid. The Mishnah in Yoma 3:5 says that the time of the evening incense was between the burning of the animal's limbs and the Drink-offering. The priests took turns with the incense offering, and this was determined by casting lots between priests who had never yet offered the incense.Mishnah Yoma 2:4, "Those who are new unto the incense, come and cast lots!"

Jewish law prescribes that the ingredients used in making the incense be re-pounded twice a year. This was done in a large, movable mortar.Cf. Abot de Rabbi Nathan 41:12; s.v. . In storage, they were to be spread out in the hot summer months to prevent their mold and mildew, but in the winter months they were to be heaped up in a great pile so as not to lose their pungency.Babylonian Talmud (Kareithoth 6b), although some texts read: "During summertime, they would shake it (i.e., the pile of spices) to prevent their mildew, but during wintertime they'd pile it in a heap." It was a custom to chant with the rhythm of the mortar and pestle while pounding the spices, during which they would say: "Pound [it] thoroughly; thoroughly pound [it]." Jewish oral teaching relates that the blend of sweet savors from the compounded incense could be sensed as far away as the mountains of Machaerus (), in Transjordan.Mishnah (1977), s.v. Mishnah Tamid 3:8 (p. 585)

Purpose Some suggest that the command to offer incense was to purify the air and to perfume it, in order to mask the bad odors from the sacrificed animals. Others say that the command to offer incense was to ward off evil spirits and demons,The Aramaic Targum of Song of Songs 4:6 while still others say that the purpose was to atone for the "evil tongue," spoken by one person against another.Babylonian Talmud (Yoma 44a) The Zohar (Ki Tisa) states that the purpose of burning the holy incense was to mitigate and render impending judgments less severe. Philosopher and Rabbi, Maimonides, rationalizes even further and writes: "There is a well-known saying of our Sages, 'In Jericho they could smell the incense [that was burnt in the Temple].' This provision likewise tended to support the dignity of the Temple. If there had not been a good smell, let alone if there had been a rancid smell, it would have produced in the minds of the people the reverse of respect; for our heart generally feels elevated in the presence of some good odor, and is attracted thereby, but it abhors and avoids bad smell."

A more esoteric explanation given for its function is to remind man that all things are from God and for God.Josephus (1981), The Jewish War (book 5, chapter 5, verse 5). The mystical tradition associates ketoreth (קְטֹרֶת) with the Aramaic word קטר, meaning a 'bind' or 'knot.' The incense thus reflects an underlying harmony and inter-connectivity in the universe, as it unites together the core essence of all forces—life, matter, and spirit—according to the recipe prescribed in the Torah.

Another purpose for burning the incense was to cover the Holy of Holies, where the Ark of the Covenant resided, with a kind of 'smoke screen'. The reason for this was to shield the priest from the presence of God. In the Book of Exodus it says that this is where God 'will meet' with the priest.Exodus 30:36 Moreover, the "cloud" was comparable to the smoke which filled the Tabernacle in future generations.Based on the Babylonian Talmud (Yoma 53a), which says: "For in a cloud I shall appear unto you, which comes to teach that he (the priest) puts in the incense a 'smoke raiser' (herb)." Cf. Midrash HaGadol, P. Aḥarei Mot (Leviticus 16:2), s.v. ד"א כי בענן אראה. This teaching, however, is disputed. Some say that this opinion was that of the Sadducees who held the view that the cloud spoken of here was the "cloud of smoke" from the burning incense. The rabbis opined differently, saying that it was the "cloud of the Divine Presence." (see: Midrash ha-Ḥefeṣ on Leviticus 16:2)

Formulæ The incense offering is first described in the Book of Exodus:

Although only four spices are specifically mentioned by name, the increased number is arrived at by homiletical interpretation of a verse in the Book of Exodus, and which raises the number of chief spices to eleven.Babylonian Talmud, Kareithoth 6b One of the general rules used in biblical exegesis and which was applied to the verse in Exodus 30:34 is this one: "Whenever a generalization is followed by a specification, which again is followed by a generalization, one does not infer from its generalization any lesson other than what is true of its specification." The generalization, in this case, is in the first use of the word "spices," followed by specified details of "rosin" (i.e. any aromatic gum resin that exudes from trees) and the "operculum" (the so-called "fingernail" spice) and "ḥelbanah". These aforesaid specified details are once again followed by a generalization, "spices." This would mean that the "spices" in question can only be those which have similar qualities to those named in the specified details; such as which are true of gum resins (e.g. Mastic, or terebinth gum resin, myrrh, balsam, etc.), and such as which is true of the so-called "fingernail" spice, etc.

For this reason, eleven spices were associated with the incense offering, and their names have come down in a BaraitaBaraita, a term applied in Hebrew for the collection of Oral Teachings which were not included in the Mishnah, a compendium of Jewish oral laws compiled by Rabbi Judah the Prince in 189 CE. found in the two Talmuds.Babylonian Talmud, Kareithoth 6a; Palestinian Talmud, Yoma 4:5 These eleven basic ingredients, besides two other adjuncts and three additional ingredients which were used to help enhance the scent of the operculum, are listed as follows: + List of ingredients used in the incense offering Hebrew Name English Name Taxonomic Name Notes הצרי Mastic resin (rosin) Pistacia lentiscus May also include other species of tree exudates: Pistacia palaestina, et al.Can be almost any resin that exudes from trees, especially the terebinth tree – Pistacia palaestina, but not limited to this resin alone. Thus is it explained by Rabbi Shimon b. Gamliel. Ishtori Haparchi and Don Isaac Abarbanel, in accordance with the Midrash Rabba and Targum, have also said that this incense was called "mastic." A description on how the mastic resin was tapped from trees growing on the island of Chios in the Aegean can be seen in Howes, F.N. (1950), pp. 307-309. bdellium (Commiphora spp.)According to R. Yosef Qafih in Saadia Gaon (1984), p. 96 (note 13), the word is synonymous with the word (naṭaf) in Exo. 30:34, and has the connotation of balsam wood (Commiphora gileadensis).