When Hashem performs open, revealed miracles, it generates awareness that even when matters seem natural, it’s Hashem’s hashgachah (see Ramban end of parashas Bo). Based on this, the Kedushas Levi (Chanukah, Kedushah 5) explains that we light Chanukah candles to contemplate the miracles, and to acknowledge that everything that happens is hashgachah pratis. ~ R’ Elimelech Biderman Shlita