The shakuhachi originally came to Japan by way of China and India from Egypt. In Japan the instrument was played exclusively by komuso monks or 'monks of emptiness' as a way to spread the teachings of the Buddha. The kumuso wore a basket over their heads when playing to symbolize their detachment from the mundane world. At the same time the sounds of the Shakuhachi were revered and experienced as  sounds of nature, sounds of the essence of life and sounds of the universe. Thus the Shakuhachi has come to represent the union of human beings with heaven and earth.

International Shakuhachi Society
"Mention of the shakuhachi immediately brings to mind the image of the basket-hatted mendicant priests called kumuso, who roamed the country during the Edo period (1600-1868). Members of a government-authorized Zen sect, Fukeshu, they regularly lodged at temples in the sect's extensive network.  Each temple had certain pieces associated with it, and the monks would customarily learn the pieces before moving on. The music, plantive and meditative, was not played for entertainment but as a form of meditation called suizen, 'blowing Zen'. The shakuhachi therefore was a religios tool, a hoki, whose purpose was to awaken the mind to a higher state of consciousness."
The Shakuhachi: Aesthetics of a Single Tone
Christopher Blasdel, Shihan in 'The Annals of The International Shakuhachi Society'
My teacher Michael Gould

"The capacity of the Shakuhachi is huge, not only as a musical instrument due to its variety of colors and special sounds, but, more so as a link or bridge between the essential nature (soul) of human beings and the essential nature (spirit) of the cosmos. The ability of the Shakuhachi to reach into people and touch something deep inside, to stir up something in a place that is not often used, is evidenced by the large number of people attracted to it that express such an experience."
Michael Chikuzen Gould

The sounds of the bamboo shakuhachi have the power to by-pass the mind and go directly into the spirit of a person. This becomes possible through masterful expressions of the spirit of bamboo with wind and breath passing through it. The bamboo plant itself is divine in nature and is the servant of humanity as tools, arts, food, structures and medicine. It humbles itself to be made into many forms for the use of humanity and is adaptable in a variety of ways for the blessing of many people and their cultures.  Perhaps it is that bamboo is identical with the spirit of humanity in the form of a plant; it certainly is in accord with the spirit of the earth and is fully represented in sacred botanical collections.

Since this page deals with origins, I would like to share the piece that inspired me to become a Shakuhachi player. This was back in 1984 when I first heard 'The Distant Cry of Deer' by Masayuki Koga.
"Who's the master?"