“To hear any flute is to be drawn into the commonality of all mankind.” Why
does the author say this?

The author considers flute music to be 'the most universal and most particular' of all music. This is a musical instrument that is common to all cultures. We have the reed neh, the recorder, the Japanese shakuhachi, the deep bansuri of Hindustani classical music, the clear or breathy flutes of South America, the high-pitched Chinese flutes, etc. Even though each of these has its specific fingering and compass yet, for the author, to hear any flute is 'to be drawn into the commonality of all mankind'. This is because in spite of their differences, every flute produces music with the help of the human breath. Similarly, despite the differences in caste, culture, religion, region, all human beings are the same, with the same living breath running through all of them.