Minna's mother writes fiction for children, asks ""What is the quality of beauty? Of truth?"" instead of ""How was your day?,"" and tacks up messages to herself--""Fact and fiction are different truths."" Intrigued but somewhat baffled by these evidences of truths she'd like to grasp, Minna (11) gets on with her own life--playing her cello in a Mozart quartet for a competition, waiting to develop a vibrato, becoming a close friend of violist Lucas (first met with a vibrato plus a frog in his pocket), joking with younger brother McGrew and his buddy, Emily Parmalee. Meanwhile, MacLachlan takes her sharply individualized characters through pivotal experiences, explores her title's ramifications as it relates to Minna's growing understanding (like her mother, Minna begins to wonder about people), and provides plenty of humor, insights, and word-play. There are several unusual elements here. All the characters are likable: interaction and growth, not conflict, propel a story remarkable for its mellow tone and sense of accord. The third-person narrative alternates between past and present tenses--the past lending fluency, the present more immediate: Joseph Jacobs knew about this, and it's tricky, but it works here. And that yearned-for vibrato makes a welcome alternative to the onset of menses as a metaphor for coming of age; with awesome skill, MacLachlan makes its arrival a satisfying culmination to a splendid story.