Al Hanissim: Derash Moshe
The reason that we light for eight days even though the miracle was only for seven days – they had enough oil for one day – is that they understood that the greater miracle was that oil burns!
They celebrated that God created a world in which oil burns. They did not want to forget the daily miracles of existence in the thrill of the seven-day miracle.
This is why we do not mention the miracle of the Menorah in Al Hanissim: We are not so confused by “miracles” that we forget the miracles of our existence every second.
Our celebration is of all the miraculous details of our lives, the ones we so easily forget and take for granted. Al Hanissim is a celebration of all the miracles in life. Pay attention! (Rabbi Moshe Feinstein – Derash Moshe)