The prophet Zechariah, who lived towards the end of the Babylonians exile after the destruction of the first Temple, says in chapter 8, that G-d tells him that all the feast commemorating the destruction of the Temple shall become to the house of Judah days of joy, gladness and holidays.

The Tamud explains this passage that all these fast days will become feast days when the Messiah comes.

The question is; when the second Temple was built, did the Jews fast and mourn on Tisha Bav as they did for the previous 70 years during the Babylonian exile after the destruction of the first Temple?

The Rishonim and the Maimonidies disagree on this issue.

For the 420 years of the second Temple, the Rishonim says that the Tisha Bav was transformed into a day of joy and gladness; Maimonidies says that Tisha Bav remained a day of mourning and fasting.

The first Temple stood for 410 years. The Babylonians in 586 B.C.E destroyed it. For the 70 years there was no Temple. The second Temple lasted for 420 years until the Romans in 70 C.E destroyed it.

How could there be a disagreement between the Rishonim and the Maimonidies over a historical fact? Either people fasted or feasted on the 9th of the AV during the second Temple period just check the historical records!

The Tamud in Eruvin states that when great Torah scholars disagree, a heavenly voice proclaims, “these and those are both are both the words of the living G-d”. How can one apply this concept to resolve the difference of opinion between the Rishonim and the Maimonidies?

The answer is that the Rishonim and the Maimonidies were talking about two different groups of people.

The book of Ezra states that when the second Temple was built, the old generation who remembered the first Temple, were weeping. The young generation, who never saw the first Temple, was rejoicing.

The Tamud in Yuma states that the second Temple was pathetic compared to the first Temple. The second Temple lacked the revealed Divine Presence, the Ark, the 10 Commandments, the Urim v’ Tumim, and a king from the Davidic family. The reason was that when Ezra called the Jews to make Aliya from Babylon and Persia, only 42,000 responded out of millions. The old generation was weeping because they remembered what the first Temple was like.

Thus, both the Rishonim and the Maimonidies are correct. The Rishonim are referring to the younger generation who feasted during the second Temple period on the 9th of Av. They grew up in the Babylonian exile and never experienced the glories of the first Temple. For them, the second Temple was the zenith of joy.

However, Maimonidies is referring to the older generation who fasted during the second Temple period on the 9th of Av because they remembered all the glories of the first Temple, which the second Temple lacked.

Thus, both the Rishonim and Maimonidies are correct.