One lights the Hanukkah candles at the entrance of his home, facing the public domain, after night has fallen. In this way, the Jewish people illuminate the darkness outside. A tremendous light emanates from these candles, a light of devotion. It draws its power from the heavenly light, which is above the bounds of nature.

The purpose of the Hanukkah candles is to illuminate the darkness. As a result of the war against the Greeks, who tried “to make them forget Your Torah and to force them to transgress the statutes of Your will” [from the Al HaNisim prayer said on Hanukkah], and especially due to the fact that they entered the Sanctuary and desecrated all the oil that was there, there was a strengthening of the force of darkness that opposes holiness. Therefore, when the Hasmoneans prevailed and defeated the Greeks, they instituted the [lighting of] Hanukkah candles in order to illuminate the darkness. And this is why the time for their lighting is after sunset, as the idea of the Hanukkah candles is to illuminate the darkness. They are positioned outside (facing the public domain), to the left of the entrance, in order to illuminate the darkness of the public domain as well, the mountains of separation, which draw [vitality] from the left side. (Rabbi Menaĥem Mendel Schneerson, Torat Menaĥem, Sefer HaMa’amarim Melukat, vol. 2, p. 131)