The significance of the numbers seven and eight permeates the parshios of Tazria and Metzora. After waiting seven days of impurity following the birth of a boy, on the eighth day the baby receives a bris milah. Seven days is the period to determine the status of the various types of tzora'as. Following a verdict of impurity brought about by tzora'as, a seven day purification period is mandated to be followed by korbanos brought on the eighth day. Parshas Metzora concludes with the halachos that govern different emissions that render an individual impure and, once again, the counting towards purification requires a time period of seven days to pass. Following the seven days, purity reaches a culmination on the eighth day when special korbanos are brought. What is so special about the number eight that it is the day of the bris and the day when purification is complete?
Seven and eight are numbers that appear in our celebration of yomim tovim. The days of sefiras haomer consist of seven counts of seven days each. After seven times seven has been completed, Shavuos is celebrated on the "eighth" day corresponding to the fiftieth day since the beginning of the counting of the Omer. The Ramban suggests that Shavuos is in a certain sense the last day of Pesach. Following the week-long celebration of the actual yom tov, the period of Sefiras Haomer links the "eighth day of Pesach" (i.e. Shavuos) to the previous seven. Similarly, the seven day holiday of Sukkos culminates with the celebration on the eighth day with Shemini Atzeres. What is the nature of this progression from seven to eight?
This procession is meaningful if we first understand the relationship between the numbers six and seven. Six is associated with the physical world. The four directions together with up and down (for a total of six) comprise the physical boundaries that surround us, whereas seven is the dimension of time. Although seven is no longer physical, it still belongs to this world, as time is only meaningful in our physical world. However, the number eight signifies the next level which emanates from an other-worldly existence. The Torah itself is a part of that other world and therefore we connect to Torah through the vehicle of "eighthly" things. We celebrate periods of sanctified time for seven days on Pesach and Sukkos but we conclude these days with the ultimate celebration of the Torah itself. Z'man Matan Toraseinu can only be on the "eighth" day. Similarly, Shemini Atzeres is the celebration of Torah itself; at that point all the mitzvos of the month of Tishrei have been performed and we may now focus our attention on the celebration of Torah. What later became known as Simchas Torah is the appropriate way to mark the day dedicated to Torah.
The eighth days in this week's parshios are likewise connected to the other-worldly gift of Torah. Bris milah and Torah are bound together as is evident from bircas hamazon in which we thank Hashem simultaneously for "al brischa she'chasamta bivsareinu, v'al torascha she'limaditanu." Both bris milah and talmud Torah are referred to as covenants that the world rests upon. A newborn enters the world of bris milah and Torah on the eighth day. The entry into a world which is beyond the physical one we reside in and even beyond the realm of time can only occur on the eighth day.
Purification goes beyond immersion in the water of the mikvah and the offering of korbanos. The last statement of the Rambam in Sefer Tahara draws our attention to the true nature of purification. Although physical water technically purifies, the real transformation occurs when one immerses himself in the waters of Torah. Just as entering a physical mikvah requires total contact with the water, with no barriers in between, so too the Torah-true path to purification of the soul mandates a total immersion in the living waters of Torah study. The transformation from impure to pure requires entering the realm of the number eight. The process can only be completed when one enters that realm and reconnects to the source of all purity, to the Torah itself.
As we read these parshios we also count the days and weeks towards kabbalas haTorah. Let us immerse and purify ourselves by entering the world of Torah, the special world symbolized by the number eight.