Musar על שבת 42:3

Some mystical elements pertaining to the Chanukah lights: We shall now proceed to explain part of the deeper meaning of the חנוכה lights which issue forth from the ירך המנורה, the stem of the candelabra (the equivalent of ירך, thigh, in a human body). The expression רגל, foot, is also found in connection with נר, light, when the Psalmist describes הר לרגלי דברך, "Your word is a lamp to my feet" (Psalms 119,105). According to Halachah, the period during which the Chanukah lights have to burn concludes when תכלה רגל מן השוק, when the foot (pedestrian) leaves the market-place, when the streets empty out. Let us get back to the meaning of the word ירך. The Torah reported that Samael succeeded in dislocating Jacob's כף ירך, thigh joint. The immediate cause for this had been Jacob's having remained alone while he had gone to retrieve some trinkets of minor value (Rashi on 32,25). No doubt these פכים קטנים, "insignificant trinkets," are of great symbolical significance. We are reminded of the פך קטן, "small cruse" of oil which the Hasmoneans found when they entered the Temple precincts after their victory over the Greeks.