The number 12 underpins our ability to count, classify, track the passage of time, and even make music without offending sensitive ears. Twelve is a multipurpose number with many, occasionally conflicting meanings. To an ordinary person, the word “dozen” sounds imprecise, and even in mathematics, the number 12 evokes contradictions; for number theorists, 12 is both sublime and evil. If you are curious about how a number can be so versatile as to be almost schizophrenic, perhaps this book is precisely what you want.

Marco Malvaldi is a chemist and the author of the “Bar Lume” mystery novels series.