Today Ezra describes the first worship service for the returned exiles. They have rebuilt the altar and dedicated themselves to rebuilding the entire temple. You have to picture them standing in the ruins of the old temple offering sacrifices and singing praises to God.
Then Ezra describes how they later laid the foundation of the temple. They had trumpets and cymbals playing as they sang Psalm 136. The priests would sing the verses and the people would sing the chorus. It was an exciting time of a new beginning and the people cheered because the new foundation had been laid. But ... it was bittersweet because many of the "old men who had seen the first house, wept with a loud voice when they saw the foundation of this house being laid, though many shouted aloud for joy." (v. 12)
Why did they weep? Perhaps because they couldn't help remember the awful sight of how the city had been destroyed back when they were children. Perhaps because they remembered how splendid Solomon's temple was and they could see that this one was going to be much smaller. Our lives are often like this. We are grateful for a new beginning and genuinely excited by what God will do, but we can't help shedding a tear over what has passed. We wonder, "Lord, will what You are doing now ever be as good as what You did then?" I think Ezra is telling us that it is okay to have those questions ... as long as we keep building.