The author says this to emphasize the universal and unifying nature of music, especially the sound of the flute. The flute's melody transcends cultural, geographical, and personal differences, bringing people together in a shared experience. The sound of the flute, according to the author, resonates with the essence of human emotion and spirit, making it something that connects all of humanity, regardless of background or circumstance.
Music, particularly an instrument like the flute, has the power to evoke emotions that are felt universally—joy, sadness, longing, peace—making it a symbol of the common experiences that bind us as humans. The sound of the flute reminds us of the fundamental similarities between people, creating a sense of shared humanity and empathy.