Béla Bartók plays a major role in many works by Peter Eötvös. The love of Bartók's music first appears in the piano piece "Kosmos". The title refers to Bartók's famous piano cycle "Mikrokosmos". However, the work also bears the title "Kosmos" because Yuri Gagarin's famous space flight was about to take place when it was written in March 1961. Eötvös was then 17 years old, and Gagarin excited the young composer's imagination. On the occasion of the 125th anniversary of Bartók's birth in 2006, Eötvös wrote a piano concerto in which he further developed Bartók's ideas and thought processes. The concerto is entitled "CAP-KO", an acronym for "Concerto for Acoustic Piano, Keyboard, and Orchestra". The piano resources are extended by use of a computer, which adds further sounds to those being played - a revolutionary technology that Eötvös wants to be understood as a symbol of Bartók's pioneering spirit. The concerto centres on the famous Bartók cascades of octaves and sixths. Eötvös has twice re-arranged "CAP-KO" for other instrumentations, e.g. as "Sonata per sei" for two pianos, three percussionists, and sampler keyboard.Among the musicians Eötvös has always admired is Frank Zappa. When Zappa died in 1993 at the young age of 42, Eötvös responded with grief and anger. He said, "In connection with Zappa's premature and meaningless death, one really cannot praise God, but must protest." He composed a piece that gives expression to this protest. Since the 150 psalms in the Bible do not deal with protest, the piece became Psalm 151: "This is the one that is not in the Bible."