R Zutra bar Toviya said that Rav said: From where is it derived that one recites a blessing over scent? As it is stated: “Let every soul praise the Lord” (Tehillim 150:6). He explains the verse: What is it from which the soul derives benefit and the body does not derive benefit from it? You must say: That is scent. Even over items from which only the soul derives benefit, one must recite a blessing and praise God.
It would appear that scent should be included in the general concept that one is forbidden to derive benefit from this world without reciting a blessing. Therefore, the question is, why was it necessary to cite a special derivation in this case?
Rashi in tractate Nidda explains that since the benefit derived from smell is less substantial than other physical pleasures, no blessing should be necessary.
Others explain that since deriving benefit from this world without reciting a blessing is likened to misusing consecrated property; with regard to those laws, smell is considered inconsequential. Therefore, no blessing is necessary (Tziyyun LeNefesh Hayya).
Others contend that since enjoying a fragrance does not fundamentally compromise the integrity of the object, it is not self-evident that a blessing is required (Rabbi Elazar Moshe Horowitz).
Two of the scents discussed by the Gemara are balsam and musk.
The balsam is likely the Commiphora opobalsamum, also known as Commiphora gileadensis, from the Burseraceae family, known in English as Balm of Gilead or Balsam of Mecca. This is not to be confused with the Balm of Gilead found in other parts of the world that is made from the resin of a different tree, the balsam poplar. The balsam is a short bush or tree of 3–5 meters with thin branches, many small leaves, and small white flowers. The highest quality perfume is derived from the resin that drips slowly from the edges of the stalks in small droplets, though the perfume is generally extracted by boiling the branches. This perfume is also used medicinally, as well as in incense and as a fragrant oil. Apparently, this is the tzori mentioned among the incense oils used in the Temple.
During the Second Temple period, the choicest balsam trees grew in the Jericho valley, and it was considered worth its weight in gold. That is why it merited its own special blessing: Who creates oil of our land.
Musk has a powerful odor. Some used it as a perfume by itself, although it is more commonly the dominant component of several fragrances used in manufacturing perfumes. Musk is extracted from the excretions of various animals, although historically, it was primarily collected from a pocket in which the glandular secretions of the male musk deer accumulate. The musk deer is the Moschus moschiferus, a hornless, deer-like animal that grows to a height of 60cm. Some associate musk with the biblical myrrh.