Since most of the African-American congregation of the First Purchase A. M. E. Church is illiterate, there is no need to purchase hymn books since they would not be able to read them. (The congregation is also too poor to afford such an expensive purchase even if they could be read.) So, when it comes time to sing a hymn, the congregation resorts to "linin' " instead. Zeebo, Calpurnia's son (who has been educated) reads each line first; then the congregation repeats what he has said in harmony. This is repeated before and after each line of the hymn.
Chapter 12 in To Kill a Mockingbird, finds Jem now twelve years old. He is getting tired of Scout always being around him and trying to do the things he does. He wants her to be more like a girl. Scout is excited because it is summer and that means Dill. However, Dill sends a letter informing them that he will be staying in Meridian this summer. The state legislature is called into session and that means Atticus has to travel to the state capital every day for two weeks. The children are left in Calpurnia's care. She decides to take them to her church one Sunday.
When Jem and Scout attend the church, they realize that most of the people there can't read. They don't have enough money to buy hymnals, so they all repeat the lines that are sung by Calpurnia's son. This is what it means by linin. Jem and Scout also see the church community come together for the sake of Tom's wife, Helen. Although they are all poor, they take up a collection for her.
What Jem and Scout learn at the church is a great lesson to them. They see the way the community has such respect for Atticus. They welcome the children with open arms, just because of who there father is. They also see how they all come together as a community, something they just don't see in their own part of town. This is a great turning point for Jem and Scout, and will help them when the trial does begin.
"Line for line, voices followed in simple harmony until the hymn ended in a melancholy murmur" (121).
In chapter 12, privileged children Scout and Jem get a lesson in doing without as they attend Calpurnia's church. Since the congregation doesn't have the wealth that white churches have, they probably don't have money for hymnals, pianos, or organs. Not only that, but many of Calpurnia's people can't read because they start working very young in an effort to help make ends meet for their families. Most of the black community's songs and stories are passed down by spoken word, from one generation to the next, as well; so, linin' is one way to keep those songs alive. Zeebo, Cal's son, leads the congregation in song and lyric line by line. The congregation holds on to the last note of their line as Zeebo sings the next line. The whole congregation sings acapella, or without a piano or organ. Acapella singing is one of the most beautiful ways to sing, too. The congregation probably knows those songs inside and out, which means they probably also know all of the harmonies that go with them. Jem and Scout are amazed at how beautiful it sounds.
basically it is when one person sings a line of a song, then the rest of the congregation repeats it. they do this in calpurnias church because few people can read.