The final day of Chanukah is customarily called Zos Chanukah , “This is Chanukah.”1 The simple reason for this name is that the Torah reading for the last day of Chanukah is “Zos chanukas hamizbeiach ,” “This is the dedication of the altar.”2

However, since Jewish custom is itself Torah,3 the saying is to be understood as meaning that this day, as the name implies, “is Chanukah,” i.e., the last day of Chanukah contains what Chanukah is all about.

Why is the eighth day of Chanukah so significant?

We find4 that Bais Shamai and Bais Hillel differed with regard to the manner of kindling the Chanukah lights. Bais Shamai maintained that the lights should be lit in descending order — on the first night, eight lights are lit, on the second night seven, and so on until the final night, when only one light is lit.

Bais Hillel , however, maintains that the lights are lit in ascending order — on the first night one is lit, on the second two, etc., until on the final night all eight lights are lit. The Halacha favors Bais Hillel.

The reason for the disagreement is as follows:5 Bais Shamai is of the opinion that we look at matters as they are in their potential state. Thus, on the first day of Chanukah eight lights are lit, for this day encompasses, in potential, all the days of Chanukah that will follow.

Bais Hillel , however, maintains that we look at things as they exist in actuality. Therefore, the number of lights lit is in accord with the actual number of days of Chanukah — the first day only one light is lit, for in actuality it is but the first day of the festival, and from that day on an additional light is lit each day.

Our Sages relate6 that Chanukah is an acronym for “Eight lights are to be lit, and the law is in accordance with the opinion of Bais Hillel.” That the name of the holiday itself is said to emphasize the opinion of Bais Hillel clearly indicates that on Chanukah particular emphasis is placed on the actual rather than on the potential.

Why?

The argument as to whether one should lean towards potentiality or actuality is in truth a dispute regarding Torah and mitzvos. G‑d gave the Jewish people His Torah and mitzvos. Torah and mitzvos therefore reflect aspects of both the Giver and the recipient. We thus find that Torah is not subject to impurity even when studied by an impure individual, for it remains G‑d’s Torah.7 On the other hand, a Torah master may forego his own honor, for the Torah is considered to be his property.8

As a result, there are two ways in which Torah is found within this world: reflecting the perspective of the Giver, or reflecting the framework of the receiver, the Jewish people.

Bais Shamai holds the former view. They therefore say that matters of Torah and mitzvos should always be viewed in their potential state, since from the perspective of the Giver, the actual exists with and within the potential.

Bais Hillel , however, is of the opinion that the most important consideration is that Torah and mitzvos affect the Jew as an imperfect created being. Therefore, until a matter has reached fulfillment, nothing has been accomplished — we must look at matters of Torah and mitzvos as they exist in actuality.

If this is so regarding all other aspects of Torah and mitzvos , how much more so with regard to Chanukah, for Chanukah is particularly connected with the recipient. This is because Chanukah differs from all other Torah festivals in that it is of human, Rabbinic origin. Thus, Chanukah in particular reflects Torah and mitzvos from the perspective of the recipient — the aspect of the actual rather than the potential.

It is for this reason that it is only on the final day of Chanukah — when all eight days have been actualized — that we say: “This is Chanukah.”

Compiled from Likkutei Sichos , Vol. XXV, pp. 243-250.