Final answer:
In the context of pastoral literature and art, when nymphs and shepherds hear the sound of rustic bagpipes, they typically dance. This reflects the celebratory and harmonious spirit of pastoral life.
Step-by-step explanation:
In traditional pastoral literature and art, nymphs and shepherds are often depicted spending their time in idyllic natural surroundings, frequently entertaining themselves with music and dance. The sound of rustic bagpipes is a typical element of this pastoral imagery, and it serves as a cue for joyful activities such as dancing. These actions are consistent with the spirit of pastoral life, which is characterized by leisure, music, and the romance of the countryside. References to these scenes are found in various works of literature and poetry, where the simplicity and harmony of pastoral life are celebrated.
Examples from poetic verses illustrate this notion: 'The shepherds' swains shall dance and sing / For thy delight each May morning,' indicating that dance and song are the reactions to music and festivity. Thus, in response to the question, when nymphs and shepherds hear the sound of rustic bagpipes, they most likely dance to the music.