Laws of Religion
Laws of Judaism
Concerning Ritual Purity and Cleanliness
from the Biblical Books of Moses (Torah)
and the Code of Maimonides (Mishneh Torah)
Our summaries of the Laws of Judaism are based on two key source texts of Jewish law (halakha): the Torah (the first five books of the Bible, often called the “Books of Moses,” namely, Genesis, Exodus, Leviticus, Numbers and Deuteronomy) and the Mishneh Torah of Moses Maimonides, written in the 12th century. The reasons for selecting these two sources, and the methods we used to prepare our summaries based on them, are explained on the page Source Texts Used for Laws of Judaism.
These summaries are emphatically not intended for use as guidance for religious practice. This work is simply a summary of what the cited texts say in the English translations referred to.
As applied to Jewish religious law, the Hebrew word often translated as “clean” and the word often translated as “unclean” have different meanings in different contexts. Sometimes these words are used to describe animal species permitted and forbidden for eating. At other times, they refer to a state of ritual purity or impurity. Such ritual impurity can often be transmitted by contact. Food that is unclean in terms of being forbidden for eating may be clean in terms of ritual purity. We use the words “clean” and “unclean” to refer to animal species that are permitted or forbidden for eating. To describe the ritual state of a thing or person we use “pure” or “impure” or, occasionally for more clarity, “ritually pure” or “ritually impure.” In contrast, the Moznaim translation of Maimonides’ Mishneh Torah uses the words kosher and non-kosher to refer to types of animals that are permitted or forbidden for eating. The Yale translation uses the words clean and unclean for all the meanings of these words.
Clean and unclean animals – those permitted for eating and those that are forbidden – are discussed in a separate section of this website on the Laws of Judaism Concerning Food.
In order to reduce the level of complexity, our summaries omit references to grades of ritual impurity, which are described in great detail by Maimonides.
Of the numerous laws concerning ritual impurity in Judaism, only certain specific ones are observed today. Most of the purity laws pertain to the necessity to be in a state of ritual purity when entering and performing certain acts within the Temple in Jerusalem, which was destroyed in 70 A.D. Since the Temple is no longer standing, these rules do not now apply. Also, all Jews are now considered to be ritually impure because those with one type of ritual impurity, namely, corpse impurity, can no longer be purified. However, certain specific practices derived from the laws of ritual purity are still followed and we have included notes in our summaries on the following pages to indicate when this is the case. For example, descendants through the male line of Aaron (the priests) still avoid proximity to corpses. Sexual intercourse is not performed with a menstruating woman (niddah) until the purification ritual of immersion in a pool of water (mikvah) is completed after the menstrual period. Washing one's hands is performed before and after eating foods for which a blessing is required. Also tableware of metal or glass that is purchased from a non-Jew will still be ritually immersed before being used for eating or drinking. Of course, these rules are followed only by those Jews who still maintain strict observance of the traditional laws, which is now a small minority among all Jews.
In some places in our summaries, we attempt to clarify what is written in the original texts by offering an explanation of the meaning. Such comments are always placed in parentheses and are usually introduced with “Editors note.” The reader should have no problem recognizing these occasional comments by us.
 Maimonides, Mishneh Torah Book 10, The Book of Cleanness, Editor’s Foreword to Yale translation, pages viii- ix.
 Maimonides, Mishneh Torah Book 10, The Book of Cleanness, Sefer Taharah; Treatise 5 on Other Fathers of Uncleanness, Chapter 2, sec 10, page 262Yale translation.
 Maimonides, Mishneh Torah Book 10, The Book of Cleanness, Sefer Taharah; Treatise 1 on Corpse Uncleanness, Chapter 5, sec 8, pages 25-26 Yale translation.
 Maimonides, Mishneh Torah Book 5, The Book of Holiness, Sefer Kedushah; Treatise 1 on Forbidden Intercourse, Issurei Bi’ah; Chapter 4, secs 1-3 (pages 44-46M 25-26Y)
 Maimonides, Mishneh Torah Book 2, The Book of Love, Sefer Ahava; Treatise 5 on Blessings, Berachot; Chapter 6, sec 1 (pages 100M 137Y) and commentary in Moznaim translation to Chapter 6 sec 1 (page 100M).
 Maimonides, Mishneh Torah Book 5, The Book of Holiness, Sefer Kedushah; Treatise 2 on Forbidden Foods, Ma’achalot Assurot; Chapter 17, sec 3 (pages 488M 248-249Y)