Final answer:
The legendary figure referenced in "A Song for St. Cecelia's Day" who tamed animals and the natural world with his lyre is Orpheus, a master musician and poet from Greek mythology.
Step-by-step explanation:
The legendary figure mentioned in "A Song for St. Cecelia's Day" who played the lyre so wonderfully that animals were tamed and even the rocks and trees followed him is Orpheus.
Orpheus is renowned in Greek mythology for his supernatural musical abilities that had the power to charm all creatures and even inanimate objects. He was considered a master musician and poet, and his talents also played a vital role in the story of his journey with the Argonauts. Additionally, Orpheus is recognized for attempting to rescue his wife Eurydice from the underworld using his melodious abilities. His status as a legendary figure is reinforced by his association with the Muses, especially being the son of the Muse Calliope, which contributed significantly to his authority as a musician and poet.