THE CRITICS: BOOKS: The Book of Delights, by RossGay (Algonquin). The title is a giveaway, but these charming, digressive "essayettes," in the manner of Montaigne, surprise and challenge more than a reader might expect. Gay, an award-winning poet, knows the value of formal constraint: his experiences of "delight," recorded daily for a year, vary widely but yield revealing patterns through insights about everything from nature and the body to race and masculinity. The fruits of this experiment—for which gardens and gardening provide a frequent, apt metaphor—attest to an imagination cultivated in hostile conditions. Gay's optimism is as easy as it is improbable, his "heart cooing like a pigeon nestled on a windowsill where the spikes rusted off."