The eighth day of Chanukah is the culmination of all of the others days of this eight day holiday. As is found in Torah, according to the parallel to the last day that a prince of one of the twelve tribes of Israel brought his gifts to the mishkan (tabernacle). Zos chanukas mizbeach – this is the dedication of the altar. The Hebrew word, chanukah means dedication. The holiday designated as such (Chanukah) commemorates the re-dedication of the Temple, after the sacrilege done by the Selucid Empire.
So, what is the significance of the eighth day to this verse from Torah? When the gifts of the twelth leader of the twelve tribes of Israel were officially bestowed, the summary in Torah, “this is the dedication of the altar” implies that the gifts of the previous days were not counted as a whole until the gifts of the twelth prince were given. As for Chanukah, it’s not over until it’s over; in other words, the finality of the holiday, speaks of completion – a sense of wholeness.
If I may go further with this, “the Eighth Day,” in and of itself represents transcendence of the natural. There are seven days a week, unlike what the Beatle’s song claims; so, the eighth day is beyond the ordinary reckoning of the weekdays. If you will, aside from all other connotations of the following word, the eighth day is “supernatural.” May we expect great miracles in our lives, looking forward to the transcendence of Olam HaZeh (This World), when Moshiach (Messiah) is anointed with oil, at the beginning of his reign from Jerusalem, at the time of the Third Temple’s dedication, ushering in the Sabbatical Millenium, the first part of Olam Haba (the World to Come).