The poem is clearly a Petrarchan sonnet since it follows its structure. The poem consists of fourteen lines made up of an octave (verse of eight lines) and a sestet (six lines).
As far as sound devices are concerned, these are used by the poet to emphasize or enhance the impact of what he says. These include rhyme, meter, alliteration, assonance and onomatopoeia.
In this poem, Donne breaks away from the common ABBAABBA and CDECDE pattern normally found in Pertrarchan sonnets. He retains the normal rhyme scheme in the octave but deviates in the sestet, where the rhyme scheme is, in this instance, CDDCAE. It is clear that he has done this deliberately for emphasis. Normally, the octave presents a problem and the sestet presents a resolution. By using a regular rhyme scheme, the poet binds sections and creates unity. This much is evident in the octave. The sestet, however, seems to break up.
'Eternally' in line 13 rhymes with thee, me, be and delivery in the octave. By doing this, Donne connects the sestet to the octave. The purpose is obvious - 'we wake eternally' is emphasized and creates a contrast to Death's supposed finality when he takes the best men. However, the link becomes clear when we learn that Death only delivers men's souls, 'and soul's delivery,' so that they may arise again and enjoy eternal life.
'Die' in the last line of the poem does not rhyme with any other word. This makes it stand out and emphasizes its importance. The speaker says 'Death, thou shalt die,' which seems paradoxical but can be understood since, when there is eternal life, there can be no death.
Another sound device Donne uses is alliteration throughout. This is used for emphasis and is identified by the repetition of consonants in consecutive words in a line. Note, for example, the repetition of the 't' in line three:
For those whom thou think'st thou dost overthrow
It is as if Donne is mouthing a 'tut, tut, tut' for Death's arrogant belief in its power. Poor Death, you are so pitiful in believing that you are so great, but I know of something even greater.
Repetition is also used effectively as it enhances the rhythmic quality of the sestet and also lends emphasis to the speaker's point about how ineffective death actually is:
And dost with poison, war, and sickness dwell,
And poppy or charms can make us sleep as well
And better than thy stroke; why swell'st thou then?
The speaker states that death is no better than sleep so why should it be so conceited?
In line six, the poet also uses assonance, which is the repetition of vowels in stressed syllables.
Much pleasure; then from thee much more must flow,
In this instance, both the assonance and alliteration work together to create a powerful image which challenges Death and mocks it, stating that it has to do much more since rest and sleep, which are similar to death, provide much pleasure. If Death wants to be feared and respected, it has to be greater, which it evidently cannot be.
In the final analysis, Donne mocks Death and declares that it has nothing to brag about for it cannot conquer the everlasting power of the soul which is unaffected by its icy grip and will continue to exist for time immemorial.