More Perfect Than the Moon by Patricia MacLachlan, 2004.

This is the first book in the Sarah, Plain and Tall Series that is narrated by Cassie, the younger daughter in the family. 

By this time, Cassie is about eight years old, and her grandfather, who rejoined the family in the previous book, has been living with them for a few years.  Caleb has also found a girlfriend (Violet, Maggie and Matthew’s daughter).  When Cassie writes entries in the family’s journal (started by Anna in the first book), they are partly fantasy, like when she thinks that Caleb and his girlfriend will someday marry and go to live in Borneo, where they will eat wild fruit.  When Caleb tells her that the things she’s writing aren’t the truth, she says, “It is my truth.”  (Oh, criminy!  I hate it when people say that.  Well, she doesn’t really mean it in the sense that I’m sick of hearing it.  I like games of pretend, but only those where the people playing them realize that it’s both a game and pretend.)  Fortunately, it’s just that Cassie is an imaginative child, and most of what she imagines is wishful thinking about things she would like to see happen.  With Cassie, the journal becomes not just a documentary of family events but of her feelings about them and what she imagines.

As Cassie grows more observant because of her writing, she notices that her mother’s behavior is changing.  Sarah is sleeping a little more, and she doesn’t always want to eat. Cassie worries that she’s sick.  Then, one day, Sarah faints.  Jacob takes Sarah to the doctor, and in the journal, Cassie writes about how her mother is well and will bring home a perfect present for her, “More Perfect than the moon,” in the hopes that it will come true.

When Sarah comes home and Cassie tells her what she wrote, Sarah says that it is true because she is pregnant.  Her perfect present will be a new baby.  Cassie doesn’t think that a baby sounds like a perfect gift.  She doesn’t want the baby because she doesn’t want things to change.  She is determined not to love the new baby.  Anna (who is now engaged to her boyfriend, Justin) tells Cassie that she didn’t love her at first, either, but she came to love her.  When Cassie asks Anna what made her love her as a baby, she says that she couldn’t help it and that she’ll understand when the new baby arrives.  All the same, Cassie can’t help but wish her mother would give birth to a cute little lamb instead.

Then, Cassie hears Sarah telling her friend, Maggie, that she thinks she’s too old to have a baby.  Cassie knows that Anna and Caleb’s mother died giving birth to Caleb, and she worries that the same thing could happen to her mother.  She thinks that the “terrible baby” is putting her mother’s life in danger.  Sarah tells her that’s not really the case, that she just thinks that it will be difficult to run after a young child again.  Still, Cassie worries and tries to keep an eye on her mother.  Sarah tells her that it isn’t necessary and that she will let her know when she needs her, like when the baby is going to be born.

As everyone guessed, Cassie’s feelings about the baby change once he arrives and she sees him for the first time.  At one point, Cassie admits to Sarah that some of the things she writes in her journal are nasty, but Sarah understands and says that one of the reasons to keep a journal is “To put down feelings. That way they don’t clutter up your head.”  Sarah knows that Cassie has a lot of worries about the new baby and the changes that will come in their family, and she knows that the journal is a way for Cassie to sort out her feelings. Once Cassie gets her worries and bad feelings out of the way, she is better able to move on to better things. Journals can be therapeutic.

The book is available to borrow and read for free online through Internet Archive (multiple copies).