Considering the title the intelligent reader focuses his attention on the most stressed word, that is "Glass" and he's curious about the meaning of it. 

Indeed, does glass mean a mirror? Or a window? Or a pari of glasses? 

These questions are a sufficient reason to go on reading the text, but just reading the second line the reader realizeS that the word glass has the meaning of a mirror.

Looking at the layout the reader can easily notice that the poem is arranged into 3 quatreins, which have different functions. For example the function of the first one is introducing the poem.

The reader can also realize that each line starts with the capital letter and the 3rd one of each stanza is the longest. As a consequence the reader guesses that the poet wants to communicate the most important meassage in these lines.

As for the phonological level the reader can note that the poet uses the alternating rhyme, allitterations and lots of figures of speech. For example the personification of the word Time , which starts with the capital letter or, as we have already seen, the metaphor of the word glass.

One more careful reading makes the intelligent reader to understand that there are some deviations in words’ order, such as what happened in line 8. So noticing the deviations the reader may be curious about the reasons and the effects of this choice.

An additional device that the reader didn’t notice just looking at the layout is that  the poet uses the reporter speech and direct speech, maybe to emphazises his message.

The semantic choice of the verb TO WASTE suggests that the speaking voice is getting old an waiting his endless rest, indeed the poet projects the image of a person who passively suffers at the hands of others. The poem also makes the reader to reflect on the role of time