What does “in tune with itself” mean?

Most old shakuhachi made in Japan were not made to the Western pitch standard of the orchestra (A=440hz). Modern shakuhachi is made anywhere from A=440hz-444hz. So, if a flute is not tuned to what is acceptable, it is said to be “in tune with itself” (assuming that the maker drilled the holes in the right places to begin with). This means the scale of the notes (the finger holes) all respond with integrity in two octaves and in relation to the natural pitch of the shakuhachi. Well made shakuhachi, old or new, are in tune with themselves. If the average player has to adjust more than two notes across two octaves with Meri or Kari to play in tune, that shakuhachi is not considered in good tuning.

Zen saying for Perry.