Each volume in the "33 1/3" series focuses fanatical intensity on a single renowned album by giving writers free reign to analyze, contextualize and rhapsodize about their favorite albums. Michaelangelo Matos -- like Prince, a Minneapolis native -- was only 12 when Sign 'O' The Times came out in 1987, and the dense, double-disc opus initially baffled the youngster who'd gobbled up 1999 and Purple Rain. Eventually it won him over; Matos writes, "[Sign is] the greatest fucking thing I have ever heard in my life." Hence, this book. The author's obsession with Prince's oeuvre rings as loudly as the Purple One's snaky guitar solo on "U Got the Look," but Matos also manages to put Sign in proper context with wit, succinct acuity and an omnivorous musical interest that enables him to draw intriguing comparisons and contrasts. But besides putting the magnifying glass on what many consider Prince's most important and ambitious album, Matos touches on Prince's tumultuous family life, racial and class attitudes in Minneapolis, and the sonic ecology of 1987. Like all 33 1/3 books, this is geared toward hardcore fans. But even though I'm certainly not obsessive about Prince's output, Matos' writing spurred me to re-examine (and find new appreciation for) a masterly Sign of the times.