Israel encamped there [as one united people] facing the mountain.
G-d's presence refuses to dwell amid discord and disharmony. Only when the Jews were unified in harmony with each other could they achieve the harmony with G-d necessary in order to receive His Torah.
The same applies today. Anyone can study the Torah, of course, but the Divine inspiration that grants us additional insight and allows us to sense G-d's presence in the Torah is ours only when we are actively concerned for our fellow human beings.
There is an additional lesson here. The Jews were able to unite at Mount Sinai because they were "facing the mountain" -- i.e., focused on the Torah. Since we all possess different intellectual faculties, emotions, character traits, and viewpoints, there is no natural way that we can maintain our individuality and still function as one unified body. Only if we are focused on G-d do our differences suddenly cease to be obstacles to unity. Our differences still exist, for they are all necessary in order to fulfill our collective Divine mission. But our shared devotion to G-d's will transform these differences into stepping-stones toward our goal rather than barriers to it.
From Daily Wisdom