Sound. . . if you look at bats you know that navigate with sonar, they're like you know they're very precise. They can even see a bat head towards a building and swerve away, but you'll see a bird that doesn't. . . you know smash right into a glass window. It's very funny.
In dealing with those who share his bed, the enlightened ruler may enjoy their beauty but should not listen to their special pleas.