The Sidra of Vayelech is usually read on the Shabbat after Rosh Hashanah. And the Rebbe establishes the connection between its content and its place in the calendar. The Sidra describes how Moses, having finished putting the Torah into writing, handed it to the Levites to be placed in the Ark in the Holy of Holies. Rosh Hashanah and Yom Kippur are, in another dimension, the Holy of Holies of the Jewish year. The Sicha therefore searches out the meaning of the Holy of Holies and its relation to the world outside. Are the holy and the profane two distinct and separate realms? Is sanctity confined to special places and appointed times?
1. The Ark, the Tablets and the Torah In Vayelech, Moses commands the Levites with these words: “Take this book of the Law, and put it by the side of the Ark of the Covenant of the L-rd your G-d….” 
The Talmud  records two conflicting interpretations of the phrase “by the side of the Ark.” One maintains that the Sefer Torah was placed inside the Ark, together with the tablets on which the Ten Commandments were engraved. The other holds that it was placed outside, on a ledge which projected from the side of the Ark. Both agree, however, that it was within the area of the Holy of Holies. Thus the Holy of Holies contained both the written Sefer Torah and the engraved tablets.
We can see that the tablets were appropriate to the Holy of Holies, because both were miraculously in space and at the same time beyond it. The Ark had physical dimensions. It was 2 1/2 cubits in length, and 1 1/2 cubits in height and breadth. And yet it occupied no space. For it is recorded that the Holy of Holies was 20 cubits wide, and yet that the Ark had a free space of ten cubits on either side. The Talmud  resolves the contradiction by saying, “We have it as a tradition that the place of the Ark… is not within measured space.”
Similarly the letters of the tablets, although they were letters that could be read and measured, they had no substance apart from the stone. In particular, the (final) mem and samech were preserved by a miracle.  They are closed letters, so the stone which they surrounded was joined to nothing, but was kept in place by G-d. The letters, in other words, were in space but not of it.
But what was the relation of the Sefer Torah to the Holy of Holies? Its letters were written. They were ink on parchment. There was nothing miraculous about them.
2. The Holy of Holies and the World The Holy of Holies contained in space and time what was above space and time. But its ultimate purpose was that this miracle should spread its light outwards, to the Priests’ Court, the Court of the Israelites, the Women’s Court, the Temple Mount and beyond, to all the nations of the world, to make them all aware that the Infinite may be found in the finite, that G-d dwells within the world.
Therefore, the Sefer Torah was housed in the Holy of Holies, as an intermediary between this inner sanctum and the world. For the Ark and the tablets represented complete effacement in the presence of G-d. They occupied no space: They were something become nothing. But the letters of the Torah were tangible, written in ink on parchment. Thus the Torah is the medium through which the light of G-d reaches the world which lives in time and space.
3. Rosh Hashanah and the Year In Chassidic thought, Rosh Hashanah has a particular spiritual characteristic. Throughout the rest of the year, we serve G-d mainly within the limits of our reason, and even the self-sacrifices we make relate to our understanding of the needs of the hour. But on Rosh Hashanah we reach a state of self-effacement which is totally beyond reason. We are not pursuing a rational objective: We are responding to a revelation from a source beyond our understanding.
This state, though it belongs to Rosh Hashanah, must not be confined to it. Throughout the rest of the year, while we live and behave within our rational framework, we must carry with us that inspiration of something higher than that which reason can grasp. It is like the Holy of Holies and the letters of the tablets: Though they had their location in space, they gave light to the whole world. And though Rosh Hashanah has its location in time, it illuminates the whole year.
4. The Preparation But for this to happen there must be a preparation. And the clue lies in the opening sentence of the Sidra we always read before Rosh Hashanah, Nitzavim: “You are standing this day, all of you, before the L-rd your G-d: Your heads, your tribes, your elders and your officers… from the hewer of your wood to the drawer of your water.” Every Jew must attach himself to the community. Even the “heads (of) your tribes” must not stand aloof from the “drawer of your water.” Jewish unity demands no less than “all of you.” The Jew who breaks through social distinctions to become one with the whole community, breaks through the distinctions of time as well. He brings the spirit of Rosh Hashanah into the rest of the calendar, and spreads its blessings throughout the year.
(Source: Likkutei Sichot, Vol. II pp. 407-8)
FOOTNOTES  Devarim 31:26.  Baba Batra, 14a, quoted by Rashi, Devarim, Ibid.  Yoma, 21a.  Shabbat, 104a; Megillah, 2b.