The Rabbis teach that the precept relating to the lighting of a candle
at the Feast of Dedication applies to a whole household, but that those
who are particular light a candle for each individual member, and those
that are extremely particular light up eight candles on the first day,
seven on the second, decreasing the number by one each day. This is
according to the school of Shammai; but the school of Hillel say that he
should light up one on the first day, two on the second, increasing the
number by one each of the eight days of the fast.... What is the origin
of the feast of Dedication? On the twenty-fifth day of Kislev (about
December), the eight days of the Dedication commence, during which term
no funeral oration is to be made, nor public fast to be decreed. When
the Gentiles (Greeks) entered the second Temple, it was thought they had
defiled all the holy oil they found in it; but when the Hasmoneans
prevailed and conquered them, they sought and found still one jar of oil
stamped with the seal of the High Priest, and therefore undefiled.
Though the oil it contained would only have sufficed for one day, a
miracle was performed, so that the oil lasted to the end of the week
(during which time more oil was provided and consecrated for the future
service of the Temple). On the anniversary of this occasion the Feast of
Dedication was instituted.
THE TALMUD, _Shabbath_, fol. 21, col. 2.