6 Days of Hoshech
Paraphrased from the Ben Ish Hai Sephardic Haggada, which quotes the Ben Ish Hayyil, vol. 3, derushim on Shabbat Hagadol, Derush 3 (which I don't own and HebrewBooks.org unfortunately only has the first 2 volumes, so I couldn't verify)
The midrash says that first 3 days of darkness were dark, but the next 3 days of darkness contained palpable darkness, where no one could even move.
As we know, one of Hashem's days correspond to 1000 years. The Ben Ish Hai writes that the first 2 millennia were full of palpable darkness. Then, in the third millenium, Avraham Avinu taught the world monotheism, and the darkness wasn't as thick and palpable. Hashem's presence was felt throughout this period - the darkness was no longer felt. This not-so-thick darkness lasted throughout the third millennium (which contained the giving of the Torah and the building of the first Beit Hamikdash), the fourth millennium (which contained both Batei Mikdash and the Tannaic era) and the fifth millennium (which contained the Amoraim, Geonim, and early Rishonim, including Rashi and Rambam). In the sixth millennium, however, the darkness became thick again, as only few (like the Ariza"l and others) had the divine inspiration that made Hashem's presence felt constantly. So, millennia 1,2, and 6 have the thick darkness, while millennia 3,4, and 5 had not-such-thick darkness.
In the darkness, we are blinded to think that material possessions have value. When Mashiah comes, however, ולכל בני ישראל היה אור במושבותם - to the Jewish people, there was light in their dwellings - we will be guided by Hashem's light to know what we should truly be valuing.
I remember a devar torah I heard as a kid that the letters that come before the letters that comprise the word וימש (from וימש חשך) spell out הטלר Hitler, ימ"ש. With the Ben Ish Hai's derasha in mind, we can see how the Holocaust was the epitome of palpable darkness of the sixth millenium. It's taken 65 years for the sun to rise. Let's hope that the full sunrise occurs soon.