People are always running around saying that reading a Shakespearean sonnet is a lot like listening to a beating heart. That's true, and we talk about it more in our "Form and Meter" section. But we think there's a lot more sound going on in this sonnet. For example, think about the third quatrain for a minute:
Yet in these thoughts myself almost despising,
Haply I think on thee, and then my state,
Like to the lark at break of day arising
From sullen earth, sings hymns at heaven's gate; (9-12)
Here, the speaker compares his newly elevated mood to a bird that rises up and "sings" at the gates of heaven, right? Well guess what. The entire quatrain actually sounds like music. Did you notice the way the word "sing" is repeated three times here (in the words despising, arising, and sings)? When our speaker utters these words, the whole quatrain seems to sing, sing, sing—just like a lark, or a person singing a "hymn" (a religious song of praise). When you think about it, the sonnet has pretty much turned into the kind of "hymn" our "lark" is singing in the poem. And it's all thanks to Shakespeare's keen ear for sound. Cool.