Complex sentence: By the mid- 1960s, he was associated with author Ken Kesey and the "Merry Pranksters", and in San Francisco, with his partner Zach Stewart, Brand produced the Trips Festival, an early effort involving rock music and light shows.
Split into simpler sentences: By the mid- 1960s, Brand became associated with author Ken Kesey and the "Merry Pranksters". With his partner Zach Stewart, he produced the Trips Festival in San Francisco, an early effort involving rock music and light shows.