2.1 Formal Structure and Closure
The first thing to clarify here is the significance of repetition in the study of poetic closure. Nothing is qualified to be categorized as formal or thematic elements unless it is repeated systematically. The physical features of language – as in rhyme and alliteration—or the relations among such features – as in stress patterns and syllable counts – are describable in terms of the structural principles evinced by the form of a poem. The same applies to metrical feet, which are also not counted as formally functioning and significant until they are repeated in connection with other feet in a line.

Repetition is not always as obvious as in the following lines:

Come forth, come forth, the gentle Spring,
And carry the glad newes, I bring…
Taken from “Song” by Ben Jonson, these lines contain the most apparent type of repetition – not “systematical” but “occasional”. The repetition may take shape as being separated, and sometimes involve with either formal or thematic elements, or both. Those elements may reinforce or conflict with one another:

Uprose the merry Sphinx,
  And crouched no more in stone;
She melted into purple cloud,
  She silvered in the moon;
She spired into a yellow flame;
  She flowered in blossoms red;
She flowed into a foaming wave;
  She stood Monadoc’s head. (“The Sphinx”, Ralph Waldo Emerson, 1965)

Most importantly, the systematic repetition, which creates meter, rhyme pattern, and stanzaic form, is itself a complex phenomena with multiple effects. Its variety and complexity make it impossible to generate any principle to illustrate the relation between itself and any other poetic structures.
(Smith 1968, 39) However, what produced by systematic repetition enhance a closure in different but observable ways. For example, meter, usually functioning to create the succeeding lines as a pure systematical repetition, brings forward the sense of continuity and integrity, may be a force for closure when it cease to function in this way, by simply using a shorter or longer line; it may also serve to strengthen a closure by going back to a norm after a deviation. As for rhyme patterns, they enhance a sense of closure only in isolated couplets, but do not always have this effect when it comes to blank verse and free verse.

Different formal structures are built up by elements differently and conclude in various ways. Sonnet is one of the most determined conventional structures, which means it is the easiest for the reader to anticipate the point of the closure; in stanzaic forms, the appearance of certain thematic elements may result in the foreseeing of closure, and the repetition of certain stanza may also create the sense of closure; the rhymed couplet may function as a force to continue for being a systematic repetition, or as a force of closure for its completeness of a formal structure; in blank verse, where formal structures are highly unpromising effect closure, a structure can also be created, which maintains reader’s expectations to continue and finally gratifies the expectations of closure; even in free verse, despite as the less a form is determined, the closure is more dependent on thematic effects and non-structural devices, if a unit is considered rhythmic, it certainly follows a certain formal principle constructing the stress pattern and the rhythmic effect.

2.2 Thematic Structure and Closure
As mentioned above, the formal elements are of the physical features of language, naturally, the thematic elements are of the symbolic (also equivalent to “conventional” in this case) properties of language. That is to say, to which extent thematic elements are effective to reader, lies in the reader’s response to the language used in the poem. The response depends on the reader’s familiarity to the thematic elements, his life experience (may influence the imaginary experience during reading), the symbolic features of these elements in the reader’s cultural environment, and so forth. 罗伯特•洛威尔的诗歌结尾(4):http://www.751com.cn/yingyu/lunwen_8497.html