The sound device illustrated in the bolded text, "When the wind stirs soft through the springing grass," is alliteration.
Alliteration involves the repetition of the same initial consonant sound in words that are close together. In this example, the "w" sound is repeated in "when" and "wind," and the "s" sound is repeated in "stirs," "soft," and "springing," demonstrating the use of alliteration to create rhythm and emphasis in the text.
