Have you ever wondered why there are so many kinds of mustard but only one kind of ketchup? Or what Cezanne did before painting his first significant works in his 50s? Have you hungered for the story behind the Veg-O-Matic, star of the frenetic late-night TV ads? Or wanted to know where Led Zeppelin got the riff in “Whole Lotta Love”? Neither had I, until I began this collection by the indefatigably curious journalist Malcolm Gladwell.