You really need to read the Collected to understand Williams. The various Selecteds out there really dont do this remarkable poet justice (though the review I read of Pinskys new edited volume of Williams was positive--havent checked that out yet). Williams was not just an Imagist poet, writing about how much depends on that red wheelbarrow, not just a free verse confessional poet of the late books, inspiration to Robert Lowell, the one who allowed him and Snodgrass and Plath and Sexton to break through back into life. Williams was a radically experimental, avant-garde poet who explicitly modeled his poetic practice on modernist industrial design, on Duchamps readymade esthetics, on Cubist simultaneity and fractured depth and ground, on Transcendentalist notions of notching the present moment on your stick, to misquote Thoreau, of basically being here now in the moment of the reading experience, experiencing reading as an almost religious act. He gave his whole heart and mind and life to the craft and study and practice of poetry, and is not easily summed up. Get Vol. 1 as well!