|The act of washing
was preformed to correct a condition of ritual impurity
and restore the state of ritual purity.The ritually impure or (
unclean) person is prohibited from per forming certain
functions and participating in certain rites. Ablution,
following a with drawal period in and ,in some cases,
other special rituals, render him again "clean"
and permit performance of those acts which his impurity
Ablution must not be confused with washing for the sake of cleanliness.
This is evident from the requirement that the body be entirely clean before ablution (Maim Yad, Mikva'ot 11:1),but there may nevertheless be some symbolic connection. The ablutions, as well as the impure ties which they were deemed to remove, were decreed by biblical law, and understood by the rabbis in religious not hygienic or magical terms. This is shown by R.Johanan b.Zakkai's to his disciples who had questioned an explanation he gave to a non-Jew about ritual purity;"'The dead do not contaminate and the water does not purify.'It is a command (gezeirah) of God and have no right to question it"(Num. R. 19:4).
In the first type of ablution The person or article to be purified must undergo Total immersion in either mayim chayyim Ð("live water"), i.e. a spring, river, or sea, or a mikveh, which is a body of water at least 40 se'ahs(approx. 120 gallons) that has been brought together by natural means, not drawn. The person or article must enter the water in such a manner that the water comes in contact with the entire area of the surface. According to law one such immersion is sufficient, but three have become customary.
Total immersion is required for most cases of ritual impurity decreed in the Torah. Immersions were required especially of the priests since they had to be in a state of purity in order to participate in the Temple service or eat of "holy" things.
The high priest immersed himself five times during the service of the Day of Atonement. Other individuals had to be ritually pure even to enter the Temple. However, it be came customary among the Pharisees to maintain a state of purity at all times, a fact from which their Hebrew name Perushim ("separated ones") may have developed. (L.Finkelstein, The Pharisees (1962),76ff; R.T.Hereford, The Pharisees(1924),31ff.).
Total immersion also came to form part of the ceremony of conversion to Judaism, although there is a difference of opinion concerning whether it is required for males in addition to circumcision, or in lieu of it Yev. 46a).
destruction of the Temple, or shortly thereafter, the
laws of impurity have been in abeyance. The reason being,
the ashes of the red heifer, which are indispensable for
the purification ritual, are no longer available. This,
everybody is now considered ritually impure. The only
immersions still prescribed are those of the niddah and
the proselyte, because these do not require the ashes of
the Red Heifer and because the removal of the impurity
concerned is necessary also for other that purely sacral
purposes (entry into the Temple area, eating of holy
things). The niddah is thereby permitted to have sexual
relations and the proselyte is endowed with the full
status of the Jew.
Maimonides decided (Yad, Issurei Bi'ah 13:7), that a proselyte who immersed him self in the presence of only two members of the Bet Din is not a proselyte.