Sculptural incisiveness is just one of the characteristics of style in Death of a Naturalist.

What chiefly makes these early poems Heaney's own is another, complementary quality. Put briefly, it is a sensuous, vital energy which determines their diction, imagery, and prosody. To an unusual degree details register with an immediacy on the reader's senses. Note for example this image in "Death of a Naturalist": "the warm thick slobber / of frogspawn that grew like clotted water." Much of the effect derives from the gross, labial "slobber," but in "clotted water" the substance verbally thickens into tangible density. (p. 37)

Augmenting the physical authenticity and the clean, decisive art of the best of the early poems, mainly the ones concerned with the impact of the recollected initiatory experiences of childhood and youth, is the human voice that speaks in them. At its most distinctive it is unpretentious, open, modest, and yet poised, aware, fundamentally serious despite its occasional humorous or ironic turn. Within an anecdotal, sometimes colloquial, or matter-of-fact context it can be terse, suddenly dramatic, charged with emotion, shock or wonder breaking through understatement. It is flexible, open to modulations and complexities of tone. Generally the rhythms are natural though in accord with the predominant pattern and metrics of a given poem….

Nor would I begin to claim for it the mastery of Yeats or Frost, but it does show that he had learned something of their skill in crossing natural speech with traditional verse structure: form and a living speech working together. (p. 40)

In "Death of a Naturalist" … Heaney most successfully exploited the qualities I have described so far. The poem begins with seemingly matter-of-fact description…. But the description prepares for the grotesque initiation [the young boy] would undergo on a later occasion…. The poem is uniquely Heaney's, the high point of his achievement at this stage of his development. The details at the end are at once true to the nauseating reality of the frogs and to their surreal psychological implications—all the obscure but immediate sexual turmoil of puberty and adolescence nightmarishly concentrated, erupting in the repulsive images.

To consider the volume [Death of a Naturalist] as a whole, however, is to become aware of its unevenness; we should not expect every poem to reach the level of [the title poem]. As the poet tested his new-found skills with a variety of subjects and modes, he wrote some poems in which technique turns into manner. Now and then, for example, the attempt to infuse the poems with energy degenerates into forced metaphor. (pp. 41-3)

[The impact of "Waterfall," for example,] is reduced by the excess of imagistic ingenuity. Ordinance and military terms in this poem and others threaten to become a metaphorical tic. (p. 44)

The love poems in Death of a Naturalist are unpretentious and direct in their feelings yet undistinguished. (p. 47)

But about a third of the poems in this first book … established Heaney's as a voice to be reckoned with. The successes arose from his risktaking, the virtuoso prosody, the bold word choices, the delving into the potentially sentimental subject matter of recollected childhood and adolescent experience on a farm. Dangers lay in the method. The words, for instance, that so characterize his style. Heaney words such as slobber, soused, plumped, knobbed, and clotted, are susceptible to overuse, to the possibility of eventual self-parody, though it was by running this danger that he gained an earthy concreteness; also his diction would undergo a continuing evolution in the succeeding two volumes. He would extend and deepen his subject matter, too, and one means of advance would be to explore more fully those forces underlying plain sense and observation. (p. 48)