Read this poem: how like a winter hath my absence been from thee, the pleasure of the fleeting year! What freezing have I felt, what dark days seen! What old becember's bareness every where! And yet this time removed was summer's time; The teeming autumn, big with rich increases, bearing the wanton burden of the prime, like widow'd wombs after their lord's decease: yet this abundant issue seem'd to me but hope of orphans and unfather'd fruit; for summer and his pleasures wait on thee, and, thou away, the very birds are mute; or, if they sing, 'its with so dull a cheer that leaves look pale, dreading the winter's near. Where does the tone shift in the poem.

The tone of the poem changes along the lines "The teeming autumn, big with rich increases, bearing the wanton burden of the prime, like widow'd wombs after their lord's decease"

Explanation:

The poem has a tone of melancholy and sadness, but the lines "The teeming autumn, big with rich increases, bearing the wanton burden of the prime, like widow'd wombs after their lord's decease" cause a change of tone. This is because these lines talk about abundance, hope that provides a certain comfort to the reader, but quickly the tone returns to being melancholy, removing this comfort previously achieved.

the swan might be a metaphor for our soul, which is ancient and timeless. the speaker wants to know where it's going and what it wants, what's the purpose in life. he asks our soul to follow him in knowing that god is us and the answer to the question "who am i" that was written on the wind of god's whim to know himself that blew over his being in the beginning of creation. and to connect to god consciously on the path to knowing him is the joy of loving him, like a bee that will grow and end our sorrows by ending desire. in that connection there is no doubt about god and existing forever.