Nearly every book or article on Tennyson alludes to the poet's characteristic ambiguity, one neither of syntax nor of meaning but inherent in his very choice of subject and thus an essential aspect of his imagination. Few critics, however, have even tried to build a unified thesis from their isolated perceptions of, for instance, Tennyson's simultaneous concern with macrocosm and microcosm, the similarity and mutual attraction of opposites in his poetry, and, over all, his assumption of the dualistic nature of things. Most references to these phenomena are as brief, but rarely so significant, as Eliot's evaluation of the success and failure of In Memoriam, which calls attention to the poem's expression at once of the most obvious and the most sensitive: “Tennyson's surface, his technical accomplishment, is intimate with his depths: what we most quickly see about Tennyson is that which moves between the surface and the depths, that which is of slight importance.”