The title of the poem "Stopping By Woods on a Snowy Evening" by R.Frost is really interesting:  first of all, the reader can notice  a graphical device  (use of capital letters) adopted by the poet in order to highlight the key-words of the poem (to stop, woods, snow and evening).

Besides, the title gives the reader useful information about the setting of the poem and raises his/her curiosity inviting him/her to stop, without telling him/her why.

The poem is arranged into four quatrains: in the first stanza, the speaking voice makes hypothesis about the possible owner of the woods, in the second and third ones he describes how his horse responds to the unusual situation on a dark evening and  in the final one he speaks about the trip he has to continue.

 The repetition of the semi-vowel sound "W" in the first stanza, sounds like the call of a wolf: as a consequence, the reader imagines the mysterious atmosphere in the wood. What's more, this sound pattern expresses  the sense of surprise felt by the speaking voice in front of this view. The reader can notice the anaphoric structure " I think I know" and the assonance of  "I" and "I".

In the second line, the alliterative use of the sound "h", seems to reproduce the sound of the wind and the reader can note an assonance ("is" and "in").                                                                                                        

There is a high density of profound vowel sounds in the third line: it adds sadness to the poem and makes it distant from the reader's position.

The high density of "s" sounds in the third stanza, seems to reproduce  the shivers of the horse, while the assonance of sound "o" in the third line adds depth to the poem. Also "the darkest evening of the year" may be a metaphor of death.

The incremental repetition of the same line in the fourth stanza, puts into evidence the length of the speaking voice's trip and adds mystery to the poem.

The reader can notice a deviation in word-order in the text useful to create a precise rhyme scheme: it links  some words in order to stick them to the reader's mind. The tone of the poem is soothing and quite sad.  Besides, the poet uses the language of sense impression to convey several  feelings to the reader.

The poet wants to tell the reader that sometimes he has to stop in his life and look round himself, because life is  so busy that it is hard to be really aware of how precious and wonderful it is: for example, the simple view of a wood covered by snow,  becomes a pleasant sight that makes you happier and quieter than lots of other things.