There is a Midrash that holds that the regular Chagim as we know them will be modified, scaled back or otherwise abolished completely. The Midrash provides an analogy that it would be like a candle in the daytime to remember miracles in an era of miracles. The Midrash stipulates that the exceptions will be Chanuka and Purim.
This is disputed; but whether or not this will be the case, such an opinion in Chazal is worth analysis.
Something about the Jews relationship with God radically changed after the Purim story. Chazal understand that as daytime ends the nighttime, so did Esther end the age of miracles.
The analogy is not clear. Should it not then be that as night ends the day, the era of miracles ended with Esther? Do we not think that the exile we are in is analogous to darkness? Why then, is exile held to be the daytime?
R’ Yonasan Eibeshutz explains that the Chagim record how God directly interceded on the Jews’ behalf at a particular time. The Purim story, along with Chanuka, are exactly the opposite. There is no direct interference on God’s part whatsoever; only behind the scenes, invisibly conducting and orchestrating events.
Purim and Chanuka will be celebrated in the era of Redemption, long after the other Chagim are superseded, because they record how in the exile, we were never alone.
R’ Shlomo Farhi teaches that when you realise God is with you, always; you are never lost, alone, or in the dark, ever again. The analogy of “as the daytime ends the nighttime” is deliberate, because in the exile, we see that God is truly with us, illustrated most clearly by the Purim story. It set the tone for the entire exile, that no matter how it looked, God would be there for us, always.
Perhaps this is what is meant by King David, when he said ה׳ שומריך, ה׳ צלך על יד ימינך. ה׳ ישמור צאתך ובואך מעתה ועד עולם – God is your guardian; God is your shadow. Hashem will protect your arrivals and departures; now and always! (Tehilim 121). The chapter is about a dawning realisation that God has always been with you, as if your shadow, “shadowing” you everywhere you go, and have been.
Here’s the kicker. You see shadows in the daytime.