When one day you make lots of money you are very happy. If you make more the next day you are even happier. If this happened 8 consecutive days you’d be thrilled every time.
If someone tells you that your friend just pulled off a very lucrative deal you would be very excited for him. However if this repeated itself every day you’d not only be less happy but at some point you’d think that it is enough already and you don’t want to hear about it.
What is the difference? Rav Eliyahu Dessler answers that when it is internal, your own happiness, each joyous occasion adds more happiness. However when it is merely external then it is just about the excitement, the newness, the thrill and that wears off with every additionaloccurrence.
Chanukah is eight days long. Those tzaddikim who connect with the Yom Tov and their joy and Avodas Hashem is internal, grow in happiness with each passing day. However, us simple people whose love of Chanukah is external, our excitement grows dimmer as the days of Chanukah progress.
With this idea he explains the Machlokes between Bais Shammai and Bais Hillel. Bais Hillel says that we light an extra candle every day to show increased happiness and increased light from the Yom Tov. Although this is not our “madreiga” it is something we should aspire too and the level we should mimic. Bais Shammai says no, we must light the candles in a way that is suitable for the level that we are on and each night we lose a candle together with our dwindling enthusiasm.
