Simplify the following text for a Grade 12 native English-speaking person.
Original: Music was provided by a host of local rock bands including Jefferson Airplane , The Grateful Dead and Quicksilver Messenger Service , who had been staples of the Fillmore and the Avalon Ballroom since February 1966 , and ` underground chemist ' Owsley Stanley provided massive amounts of his `` White Lightning '' LSD , specially produced for the event , to the gathered masses .
Simplified: Local rock bands such as Grateful Dead and Quicksilver Messenger Service provided the music , and Owsley `` Bear '' Stanley provided massive amounts of his `` White Lightning '' LSD to the gathered masses .