In Parshas Vayigash, as Yaakov Avinu is preparing to travel down to Mitzrayim, Hashem appears to him "b'maros ha'lailah - in the visions of the night" (46:2). Similarly, when Yaakov begins his journey to Lavan in Parshas Vayeitzei, Hashem appears to him in a dream (28:12). This image of receiving prophecy at night through the medium of a dream is something unique to Yaakov Avinu. The Torah never mentions an instance when Hashem spoke with Avraham or Yitzchak in a dream. Why is Yaakov the only one of the Avos to receive prophecy in a dream of the night?
The Meshech Chochma explains that Hashem appears to Yaakov in a dream when he is preparing to leave Eretz Yisrael to allude to the fact that the Shechina can appear to a navi even in the darkness of golus, but only if he already saw prophecy in Eretz Yisrael (see Moed Katan 25a). Hashem was reassuring Yaakov that He will still appear to him even in Mitzrayim because he had already received prophecy in Eretz Yisrael. Hashem shares this message specifically with Yaakov Avinu because he is the first of the Avos who leaves Eretz Yisrael for an extended period of time. Yaakov's life experience serves as a model for every future golus of Klal Yisrael. As Chazal say (Megillah 29a), "(Even when) they were exiled to Bavel, the Shechina was with them." Once the Shechina established a connection with Klal Yisrael in Eretz Yisrael, it continued to dwell amongst them even after they were exiled to Bavel.
This idea - that a connection to the Shechina that is established by day can be maintained even into the night - is also hinted to in the tefilla of ma'ariv which Yaakov Avinu instituted (see Brachos 26b). This tefilla corresponds to the sacrificing of the fats and limbs in the Beis HaMikdash. As long as an animal is slaughtered and its blood is sprinkled on the mizbei'ach during the day, its fats and limbs may be burned on the mizbei'ach any time during the night afterward. But the slaughtering of the animal or the sprinkling of its blood may not be performed at night. Only if the process of bringing the korban has begun during the day may it be completed at night, because avodah is permitted at night only if it is a continuation of the avodah of the daytime.
Yaakov is the one who instituted the tefilla of ma'ariv corresponding to the burning of the fats and limbs because it was he who demonstrated, at different times during his life, that once a person establishes a close relationship with the Shechina when he is surrounded by the kedusha of Eretz Yisrael, he can maintain that connection even in golus when he is no longer exposed to the kedusha of Eretz Yisrael.
The Rambam (Hilchos Beis Habechira 6:14-16) echoes a similar idea regarding the relationship between the kedusha of the Beis HaMikdash and that of Eretz Yisrael. He distinguishes between the first kedusha of Eretz Yisrael that was endowed at the time of Yehoshua and the kedusha of Eretz Yisrael that was endowed at the time of Ezra. Since the first kedusha was a result of the kibush (conquest) of Eretz Yisrael at the time of Yehoshua, it disappeared when Klal Yisrael were exiled after the destruction of the first Beis HaMikdash. But the second kedusha of Eretz Yisrael was not a result of kibush but of chazaka, namely the fact that Klal Yisrael settled the land when they returned from Bavel. Therefore, it did not disappear even when Klal Yisrael were exiled after the destruction of the second Beis HaMikdash.
Rav Soloveitchik explains (see Nefesh HaRav, p. 77) that at the time of Ezra, Klal Yisrael initially settled around the Beis HaMikdash and Yerushalayim, and slowly moved outward until they settled the entire land. By resettling Eretz Yisrael in this manner, they drew the kedusha of the Beis HaMikdash to the rest of Eretz Yisrael. Therefore, since the kedusha of the Beis HaMikdash, which is due to the presence of the Shechina, can never be nullified, the second kedusha of Eretz Yisrael, which drew its strength from the Beis HaMikdash, also could never be canceled, even when Klal Yisrael were exiled a second time.
A third area in which we see the far-reaching effect of a source of kedusha is the day of Shabbos. "Let us go greet Shabbos, for it is the source of all blessing. (Lecha Dodi)" Why is Shabbos considered the source of all blessing? The answer is that Shabbos is a weekly reminder that Hashem created the world (Yisro 20:11) and that he took Klal Yisrael out of Mitzrayim (Va'eschanan 5:15). Yetzias Mitzrayim highlighted that Hashem is in control of the world and that He is the Source of all blessing. Through our tefillos on Shabbos, our recitation of Kiddush, the activities we engage in on Shabbos, and the way we bid farewell to Shabbos at its conclusion (melave malka), we demonstrate how much we have internalized the messages of Shabbos and that we appreciate how dependent we are on the Ribbono Shel Olam, and that can help us draw from the kedusha and the bracha of Shabbos to the rest of the week.
This week Klal Yisrael is celebrating the 13th Siyum HaShas of the Daf Yomi. Finishing all of Talmud Bavli is certainly a monumental achievement. But what is equally remarkable is how many of the individuals who took on learning daf yomi related that the daily commitment of daf yomi not only broadened their horizons in Torah learning, but it had a ripple effect on how they and their families live their lives. It affected how they observe mitzvos in general, how they act in the workplace, how they spend their free time, even what they choose to speak about at their Shabbos tables. Sometimes we underestimate the profound impact that a religious experience can have on us. But the fact is when we infuse our lives with mitzvos and ma'asim tovim - whether it's finishing shas or simply elevating a regular Shabbos meal - we stand to benefit not just from the mitzvos themselves, but from the transformative effect that these experiences of kedusha can have on ourselves and our families.