W.S. Merwin has earned his distinguished place in American letters.  A prodigious poet, translator, and essayist, he has both a phenomenal output to his credit and an instantly recognizable lyric voice, one with rhythms so assured that Merwin can write poems without using punctuation. The Shadow Of Sirius (Copper Canyon, $22), his latest poetry collection, focuses on late-life themes like memory and time; in Merwin’s hands, each moment is both singular and rich with archetypal resonance. In a Proustian spirit, Merwin draws beautiful lyrics from a remembered patch of sunlight, a reflection in a tile, the sound of a trolley. While these moments inevitably pass, they also linger in a timeless transcendent state, and Merwin evokes this paradox in his many nature poems, celebrating the endless cyclical recurrence which, like the sky overseeing all, is “never unknown and never known.”