The theme of the excerpt from "The Giant's House" by Elizabeth MacCracken has to do with belonging and/or acceptance.
The incident in this excerpt is narrated by the librarian, Peggy, using first person point-of-view. The librarian tells the reader how James came into the small town's library asking, "I want books about people like me" (12). It is revealed that James is very tall. Not just the tallest boy in his class, but tallest in the town, maybe the state. The narrator tells us how she goes through several search threads (and terms) in order to find information for James. Through James' inquiries and the narrator's clarifications -- trying to get closer to what James was really, truly searching for -- we learn that he wants to mitigate or minimize his condition. He was looking for "cures."
"The worst book was called Medical Curiosities. I say worst now. that is hindsight . . . I found it under the subject heading Abnormalities, human. A terrible phrase, and one I knew I could not repeat to James" (12). This shows the narrator's sensitivity to James' condition. We must trust that she knows James better than we do and that her cautions are based on a knowledge of James and his temperment. She feels she could never say the word "abnormal" to James because, she felt, it would hurt him. This highlights the central conflict and, in doing so, also illuminates the major theme of acceptance/belonging.