More meditative, more provocative than his previous, much-praised work, The Milk of Inquiry is Koestenbaum’s strongest collection to date. Its most ambitious gesture is a long poem, Metamorphoses (Masked Ball), a sequence of 115 bawdy, speedy sonnets, spoken by mythological figures ghosting as historical personages-among them, Orpheus speaking as Elvis, Proserpina speaking as Freud, Adonis speaking as Cleopatra, and Daphne speaking as Wilde. Short lyrics that show this opulent writer at his most austere and a long autobiographical poem round out the collection.