“Book of Longing” is Leonard Cohen’s first book of new poetry since “Book of Mercy” was published two decades ago. It collects Cohen’s poetry written between the 1980s and the present, and also includes his wonderfully witty and sensuous illustrations, including numerous playful self-portraits. The illustrations interact with, and complement, the poetry in unexpected and fascinating ways. “Book of Longing” demonstrates the range and depth of Cohen’s work, revealing an extraordinary gift of language and visual art that speak with rare clarity, passion and timelessness.