This week's parshah
begins with the words "And it was on the eighth day."
Which eighth day? Counting from when?
The parshah speaks about a very special beginning: the first days of the actual service in the Mishkan. For many weeks now, the parshiyos have been talking about the Mishkan. We've read about the building of the Mishkan, about the kohanim who would serve there, the clothes they would wear, and the sacrifices they would bring. At the end of the previous parshah, we read how HaShem commanded Aharon the Kohain and his sons to bring special sacrifices for seven days to prepare themselves for the daily service in the Mishkan.
And now we are reading about the beginning of the actual service. During the seven days, Moshe had put up the Mishkan and taken it apart each day. On the eighth day, he put it up and left it standing. Then the kohanim began their daily service.
But why is this called the eighth day? HaShem told the kohanim to count seven days of preparation. He did not mention an eighth day. This day is new, different, and separate, because this is when the actual service in the Mishkan began. Calling it the eighth day makes it sound like it's a continuation of the seven days that came before.
One of the meforshim, the Kli Yakar, explains that the number eight is very different from the number seven. Seven symbolizes the natural, daily pattern of life, as in the seven days in the week. Eight symbolizes what is higher than nature.
HaShem put His holiness in all the things around us, but we cannot always see it openly. The number eight is connected with revealing His holiness for everyone to see. That is why the Torah calls this the eighth day, because on this day "the glory of HaShem was revealed to the entire people."
But we still ask: Calling this the eighth day connects it to the seven days which came before. Since eight is very different from seven, why does the Torah call it the eighth day?
Because HaShem wants there to be a connection between the eight and the seven. Eight is supernatural, while seven is natural. By calling it "the eighth day," the Torah shows that the purpose of the avodah in the Mishkan is to bring the special holiness connected with the number eight into the ordinary, natural things that are connected with the number seven.
Our Rabbis teach us another interesting thing about the number eight. The harps used by the musicians in the Beis HaMikdash had seven strings. But the harps which will be used in the time of Mashiach will have eight strings, because then HaShem's holiness will be openly revealed.
(Sefer HaSichos 5751, Vol. II, p. 475)