Remember what God has done for us through celebration ceremony

Nehemiah 8:13-18
On the second day of the month, They found written in the Law, which the Lord had commanded through Moses, that the Israelites were to live in temporary shelters during the festival of the seventh month. and that they should proclaim this word and spread it throughout their towns and in Jerusalem: “Go out into the hill country and bring back branches from olive and wild olive trees, and from myrtles, palms and shade trees, to make temporary shelters”—as it is written.
The whole company that had returned from exile built temporary shelters and lived in them. From the days of Joshua son of Nun until that day, the Israelites had not celebrated it like this. And their joy was very great.
They celebrated the festival for seven days, and on the eighth day, in accordance with the regulation, there was an assembly.
When they learn the full measure of their failures.
In the course of study, they rediscover the original instructions for the Feast of Tabernacles. And for the first time since Joshua they make leafy shelters to live in, as a reminder of their ancestors' desert-wandering after the exodus from Egypt.
Why?
People return from exile study the Law from Moses, let them remember their ancestors' desert wandering after the exodus from Egypt.
Remember how the Lord has protected them and led them out of slavery.
Ceremony looks meaningless, but celebration ceremony may let us remember what God has done for us.
How?
When we forget what the Lord had done for us, then we will turn to the wrong way and forgot what God said.