SUN UNDER WOOD. <i> By Robert Hass. (The Ecco Press: 88 pp., $22)</i>

The “smiling public man” W. B. Yeats saw himself become after he was appointed to the Irish senate is an unfamiliar figure among American writers. In Latin America, writers in their mature years are chosen as ambassadors or run for elected offices, while American writers’ public service tends toward the classroom. Robert Hass is the most active poet laureate of the United States we’ve ever had and he sets a standard for those who follow. He has turned the position of poet laureate into a sort of mini-Cabinet post. What was formerly a titular appointment for a well-laureled poet (with an occasional wild card such as James Dickey) is now, and one hopes henceforth, an influential post for various kinds of advocacy for the word.

“Sun Under Wood,” his fourth book and the first one in seven years, consists of only 20 poems. The voice in these poems connects with his stance as the public voice of poetry. You could give this collection to a friend who says she does not understand poetry, hated poetry ever since her sixth-grade teacher made her memorize “My Last Duchess,” and know that she would find herself drawn in. Beyond that level, however, lies a passionate inquiry into the meanings of experience--especially the nature of happiness--and a sophisticated linguistic power.

And Hass depends on the natural world. Unlike the traditional poetic gesture of the image or action in nature corresponding to an inner state, Hass turns to nature to ground himself in the swirl of emotions and events. It’s his fallback--the red foxes, windfall apples, owl’s shadows, “Creekstones practicing the mild yoga of becoming smooth.” The natural world provides a touchstone in the same wondrous sense expressed by the late William Stafford, that we have in the Earth “such a great friend, undeserved.” Hass is a particular observer of “a Western grebe diving and swimming with its crazed red eye,” “deep-rooted bunchgrass,” “the pond the color of smoky topaz”--all the details of the deep, renewing freshness of the natural world.

“Sun Under Wood” is Hass at his best. It is a book to reread, always with the lucky sense of walking through a meadow with a friend, deep in the best kind of exchange.