In what ways can Thetis be understood as a poem about transformation and power?

In her poem “Thetis”, Carol Ann Duffy presents the concept of power by following the story of Greek Goddess Thetis and her struggle to escape her male pursuer, Peleus. In the poem, we see Thetis trapped in a continuous cycle of shapeshifting into different forms in attempt to liberate herself from Peleus, however he somehow manages to outmatch her every time by changing his own form. When she transforms into a mighty lion, he becomes a hunter, waiting for her in the grass with his twelve-bore. His constant ability to surmount her is representative of the concept of power. This idea is reinforced by Duffy’s reference to The Rime of the Ancient Mariner, when Thetis shape-shifts into a great albatross, only to be shot down by Peleus’s crossbow. The mariner’s tale focuses on his ill-fated journey at sea, during which he shoots an albatross out of the sky to prove that no creature is more powerful than humans. Killing simply because he can shows a craving for a status of superiority. This idea links to the the story of Thetis, more specifically Peleus, as his motivation to persistently capture Thetis derives from his unshakeable desire to establish dominance over her. By the end of the poem, Peleus is finally able to pin her down and her desperation to escape him dissolves. This reveals the complete transformation of her identity, as she is no longer an enticing woman with the need to protect herself from forceful pursuers, but rather a mother with a new set of priorities and responsibilities.