Two Books to Sing About

What are the odds? Two books, both by English tenors and both on the nature of song. In “Song & Self: A Singer’s Reflections on Music and Performance,” Ian Bostridge, known for his intense operatic performances and lieder recitals, offers a personal inquiry of sorts. John Potter—a versatile singer whose extensive discography includes early music with the Hilliard Ensemble and tightly harmonized ’70s pop with the Swingle II iteration of the Swingle Singers—ranges across centuries and styles in “Song: A History in 12 Parts.”