Alliteration is when two or more words have the same beginning sound. In the poem there are three examples:
1) Though...thy...thou
2) crest...craven
3) shorn...shaven
Alliteration gives the text a more unified rhythm, in a way I guess. It makes the piece sound more together.
Hope this helps!
<span>A researcher may claim that variables are related to each other if test results are significant.</span>