Whitman between Impressionism and Expressionism is the first comprehensive and systematic study of Whitman's language experiment in relation to his artistic and philosophical purposes. Author Erik Thurin's focus is determined by the discovery that his linguistic innovations can be described and interpreted in terms of a dual approach closely resembling what is now called impressionism and expressionism.

A number of theoretical and quasi-theoretical remarks in the 1855 preface to Leaves of Grass and the poetry itself suggest that this approach is deliberate. Thurin postulates that it must be related to his determination to be "the poet of the body" and "the poet of the soul," impressionism representing a tendency to passively and objectively record incoming sense data, expressionism the urge to transform and use them in "the efflux of the soul." Whitman is, in fact, prophetically adumbrating a new ideal of health and power, a modern personality that is to balance body and soul.

It is autobiography anthropologically conceived. Discourse analysis allows Thurin to conclude that Whitman's poems and long sections of poems fall into three categories: (1) pure impressionism, (2) pure expressionism, and (3) a combination of both.