Intensely serious beneath a surface of lightness and wit, Kenneth Koch's poems maintain power, Denis Donoghue wrote, by rarely choosing to exert it. Koch's virtuosity - he has written many plays, an extravagant novel (The Red Robins), and short stories (Hotel Lambosa), and has done numerous collaborations with painters - seems part of a continuing and energetic attempt to write (in the words of Ariosto) things never said in prose before or in verse. Almost every poem is a new kind of poem, a new flight - in this volume, for example, the theme and variations of One Train May Hide Another, the Poems by Ships at Sea, the post-Apollinairean couplets of A Time Zone, the Chinese poetry-influenced quatrains of The First Step, and the hundred or so brief poems that together make up the poem On Aesthetics.