Four

The Four Cups at Passover. The Yerushalmi gives a few sources for the number four, the four cups from Sar HaMashkim's dream, the four languages of redemption in parshat VaEra, the four cups of tanchumin, and the four cups of puranut.

And then there are the Four Redemptions as explained in the Zohar Raya Mehemna.

But there is another four, and it was so obvious, but it only occurred to me last year: the Four Fasts.

In chronological order of their occurrence:

Asarah b'Tevet - The siege begins, Jerusalem is cut off from the rest of the land.

Shiva Asar b'Tamuz - The walls are broken, we lost control even of Jerusalem

Tisha b'Av - We lost the Temple

Tzom Gedaliah - We lose any vestige of governance, even the puppet government.

Those are the four defects of the Galut that must be repaired.

First we must regain control of the land.

Then we must regain Jerusalem.

Then we must regain the Temple.

Then we must perfect the kingship.

These are the cups of tanchumin, yet the nations mourn, these are the cups of puranut.