Why did Hashem give the Torah specifically on Har Sinai versus the other mountains? [1]
When the Torah was given, many mountains offered their services to have the momentous event transpire on their grounds. Only one mountain was chosen, and that is the famed mountain of Sinai. The Sinai Mountain contrasted from other mountains physiologically, in that it was small, not reaching to very great heights as did the other mountain, such as Mount Tabur, Mount Carmel or Mount Hermon. Nonetheless, specifically the Sinai Mountain was chosen to have the Torah given. This was due to the following reason: Height represents haughtiness which is the root of all evil and is the antithesis of Torah, as Torah can only grasped through humility. On this the Sages state [Eiruvin 54a] “If one makes himself like a desert which all step on, the Torah can be established within him”, which means that if one learns Torah with humility, without haughtiness, then the Torah can internalize within him. This is also why in prayer we first say “Venafshi Keafar Lakol Tihyeh/ May my soul be like dust before all” and only then do we say “Pesach Libi Besorasecha/Open my heart to your Torah.” For this reason, the Torah was not given on the high mountains, as they represent a high level of ego. Har Sinai on the other hand was low, which represents humility.
Why did Hashem give the Torah specifically on Har Sinai versus a valley or flat land?[2] Based on the above it remains to be understood why at all a mountain was chosen for the giving of the Torah. If the lower you are the more humility you represent, then would it not have been fitting to give the Torah on plain land, or a valley? The explanation is as follows: Although Torah requires Bittul, self-subjugation of the ego, it nevertheless also requires a feeling of self-confidence, that one feels assured that he is able to serve G-d and stand up to his evil inclination and battle it. Therefore, the Torah was given on Har Sinai which contained a minimal height, as it represents a balanced ego; an ego which is humble enough to preserve the Torah and at the same time have the self-respect to stand up for the good and battle the evil. This is why the mountain was called Har Sinai, which can also mean the mountain of hatred, as it brought hatred and enmity to the Kelipos, as through this form of service one is able to battle his evil inclination.
[1] Likkutei Torah Bamidbar p. 15
[2] Likkutei Torah Bamidbar p. 15