Tohorot ("The Order of Purities") is the sixth order of the Mishnah (also the Tosefta and Talmud). This order deals with the clean/unclean distinction and family purity. This is the longest of the orders in the Mishnah. There are 12 tractates:

1. Keilim: ("Vessels"); deals with a large array of various utensils and how they fare in terms of purity. 30 chapters, the longest in the Mishnah.
2. Oholot: ("Tents"); deals with the uncleanness from a corpse and its peculiar property of "overshadowing" objects in the same tent-like structure as it.
3. Negaim: ("Plagues"); deals with the laws of the metzora.
4. Parah: ("Cow"); deals largely with the laws of the Red Heifer.
5. Tohorot: ("Purities"); deals with miscellaneous laws of purity, especially the actual mechanics of contracting impurity and the laws of the impurity of food.
6. Mikvaot: ("Ritual Baths"); deals with the laws of the Mikvah.
7. Niddah: ("Separation"); deals with the Niddah, a woman during her menstrual cycle.
8. Makshirin: ("Preliminary acts of preparation"), the liquids that make food susceptible to tumah (ritual impurity)
9. Zavim: ("Seminal Emissions"); deals with the laws of a person who has had a seminal (or similar) emission.
10. Tevul Yom: ("Bathing (of the) day") deals with a special kind of impurity where the person immerses in a Mikvah but is still unclean for the rest of the day.
11. Yadayim: ("Hands"); deals with a Rabbinic impurity restricted to the hands.
12. Uktzin: ("Stalks"); deals with the impurity of the stalks of fruit.

The traditional reasoning for the order of the tractates (according to Rambam) is as follows. Kelim is first as it introduces the levels of impurity, and dictates to which object the various impurities apply at all. Oholot follows because it outlines the most serious type of impurity. Negaim follows because it is next in severity and because, like a corpse, a metzorah transmits tent-inpurity. Parah follows as it outlines the purification for the severe impurities already dealt with. The next stage is lesser impurities (Tohorot) and their method of purification which is immersion (Mikvaot). Niddah follows as it is also a lesser impurity but it has the extra feature of applying to only a portion of people (ie. to women). Makshirin, Zavim and Tevul Tom follow Niddah based on Scriptural order. The next stage down is impurities that are Rabbinic only (Yadaim). Finally, Uktzin is last as it is restricted and has no Scriptural source, the laws being derived from the reasoning of the Sages.

There is a Babylonian Gemara on only Niddah. This is because most of the other laws of purity do not apply when the Temple is not in existence. There is no Talmud Yerushalmi (Jerusalem Talmud) on any of Seder Tohorot.

External links

• Introduction to Seder Tohoroth from the Soncino translation