When the Saints Go Marching In

"When the Saints Go Marching In" is a very old song that talks about how happy people will be when they go to heaven one day. It was written a long time ago by people who believed in God and who thought that when they died, they would go to a wonderful place called heaven where they would be very happy.

The song talks about how, when all these people go to heaven, they will be happy and they will sing a song called "When the Saints Go Marching In." Everyone will be playing music and singing, and the saints will march in a big parade, surrounded by beautiful light and happiness. The song also mentions that some people may not make it to heaven, but that the saints will be there to greet them and care for them even if they don't get to be in the parade.

So basically, "When the Saints Go Marching In" is a song about how happy people will be when they get to heaven, and how they will sing and dance and feel a lot of love and happiness.