A principal force behind the New York School of poets that flourished at mid-century, Kenneth Koch never quite won the pride of place occupied by the likes of Frank O’Hara and John Ashbery. This volume compiles Koch’s long poems, making an eloquent argument for his unique stature. Many of the half-dozen writings run upwards of 100 pages; our favorite is “Seasons on Earth,” a melancholy glance back at ecstatic youth: “That sense that now seems almost unbelievable — / I love it, I loved it — is it irretrievable?”