Ammons' poetry may well be an acquired taste, and especially so the tight, self-definitive core of it. This is a collection of poems produced since 1964, the year of Expressions of Sea Level--his second published book, but the first of the group that made his reputation--and it reflects his development since then. The forays into long, loose vernacular ""spieling"" are offset by a more general tendency to harden and pare down; and while the long poems give easiest entry, their undiscipline only allows them to orbit the ideas the others virtually enact. They are ideas about nature, but more precisely the perception of it: hunger for comprehensive understanding yet realization that the world is only knowable in its particulars and that these will add to no comprehensible sum. Transactions between parts and whole can nevertheless be observed, fleetingly, at certain boundaries (between sound and silence, shore and sea, single creatures and enduring species) and the incalculable meshing of natural accident can be marveled at (as in ""Impulse""). But Ammons' poems are less celebrations than durable approximations in an alien form. Like the cairn in ""Apologia pro Vita Sua,"" (and Stevens' jar) they inject positive shapes into negative shapelessness and note the shared contour.