The week which is truly the happiest is the one in which the Torah portion of Lech Lecha is read.

There is a saying of the Previous Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneersohn, quoted in the name of his father, the Rebbe Rashab: "The first Torah portion, Bereishit (Genesis), is a joyful Torah portion, for in it, G-d created the world and all of its inhabitants. "Noah, however, relates the Great Flood. The week in which it is read is therefore a sad one, but it ends on a happy note with the birth of our forefather Abraham. "Yet the week which is truly the happiest is the one in which the Torah portion of Lech Lecha is read. For each and every day of the week we live with Abraham." Why is Lech Lecha, this week's Torah reading, considered the most joyful of the three? Bereishit contains the narrative of Creation. This portion relates G-d's actions, and describes how He created the world in six days. The portion tells us what G-d did, but it does not relate the deeds of the creations themselves. Noach, by contrast, deals primarily with the actions of mankind. In this Torah portion we learn about the Great Flood, about the behaviour of the people of Noach's generation, and about the deeds of the righteous Noach himself. Thus each of the first two Torah portions concerns itself with an entirely different sphere. Bereishit revolves around G-d and G-dly matters, whereas Noach concentrates on the more mundane affairs of mankind. In neither of these Torah portions is the connection between G-d and man, the higher spheres and the lower spheres, expressed. How do Jews create that connection? By carrying out the will of G-d and performing His mitzvot (commandments). When Jews observe the Torah's commandments they draw closer to G-d, binding themselves to Him with an everlasting bond. When G-d gave His holy Torah to the Jewish people, He thereby gave them the means to forge a connection between the "higher worlds" - G-d - and the "lower worlds" - human beings. The preparation for the giving of the Torah began with Lech Lecha, when G-d gave Abraham the commandment to "go out" of his native land, and Abraham obeyed. Ignoring his own personal wishes and his natural proclivities and inclinations, Abraham set off to fulfill the will of G-d to establish a "dwelling place" for Him in the physical world. Thus began the wondrous connection with G-d that continues and is strengthened with every mitzva we perform. This is why Lech Lecha is the most joyful of the Torah's first three portions. The first speaks solely of the higher worlds; the second, only about the lower. It isn't until the third portion, Lech Lecha, that the true connection to G-d first commences.

Adapted from Likutei Sichot, Volume 15