The obligation to have yiras Shomayim - fear and awe of Heaven - is one of the most fundamental mitzvos in the Torah. While this mitzvah is incumbent upon us at all times, during the period of Aseres Ymei Teshuva we are required to intensify our devotion to this ideal. The phrase that we use to refer to this period of time - "Yamim Noraim / Days of Awe" - emphasizes the greater obligation of yiras Shomayim that exists during these days. How do we achieve this lofty goal?
In Parshas Vayelech Hashem gives us the mitzvah of Hakhel, i.e. once every seven years the entire Jewish people must gather in the Beis Hamikdash to hear the words of the Torah read. The Torah states explicitly that a primary goal of Hakhel is to instill yiras Shomayim in ourselves and our children. How does Hakhel facilitate this?
The true secret of yiras Shomayim can be found in Parshas Yisro immediately following matan Torah (Shemos 20:17). Here, Moshe explained to the Jewish people that Hashem had them go through the overwhelming experience of maamad Har Sinai to instill yiras Shomayim in them. In future generations, this experience would be replicated through the mitzvah of Hakhel.
How so? The Ramban in Parshas Teruma describes the role of the mishkan (and eventually the Beis Hamikdash) as being the physical location wherein the events of matan Torah are perpetuated. The focal point of the mishkan, and later the Beis HaMikdash, was the Kodesh Hakadashim which housed the luchos, a tangible reminder of matan Torah. As such, gathering the entire Jewish people to hear the Torah read in the Beis Hamikdash is endowed with the ability to have the same affect as standing before Har Sinai[1].
It behooves us during the period of the Yomim Noraim to increase our level of yiras Shomayim. Unfortunately, we no longer have the Beis Hamikdash as a vehicle to assist us, but we still do have the study of Torah. By dedicating ourselves during these days to Torah study we can get a glimpse of the Divine Presence, enhance our yiras Shomayim, and thus properly experience the Yamim Noraim. In the merit of our rededication to yiras Shomayim may we once again experience the Divine Presence shining in the Beis Hamikdash.
[1]Even today's public reading of the Torah is a partial reenactment of maamad Har Sinai. As such, many people follow the custom to stand during krias HaTorah just as the Jewish people stood as they received the Torah at Har Sinai.