Airto Moreira

In a 1981 Musician interview, Hart talks about Airto:

"Airto gave me this Brazilian stringed instrument called the berimbau. He gave me a
quick lesson in how to play it, and I took it home to practice on.
Well, I wound up just staring into the fire  and playing this thing for
weeks. It just took over; I wouldn't accept phone calls or anything,"
laughs Hart. "Three weeks later I called up Airto and asked him what
the hell was going on!" and he explained that in Brazil the berimbau
was used to induce an altered state of consciousness for practicing
the  martial arts." Hart pauses. "The weird thing is that I've been
into the martial arts for years, but had let it go for a while, and 
then got back into it when I started playing the berimbau . . . And 
there was Airto talking about how this jungle instrument could take
you without you even knowing it!"