El Cóndor Pasa (The Condor Goes by (or Flies by)) is a song from the zarzuela El Cóndor Pasa by the Peruvian composer Daniel Alomía Robles written in 1913 and based on traditional Andean folk tunes.
It is possibly the best-known Peruvian song worldwide due to a cover version by Simon & Garfunkel in 1970 on their Bridge Over Troubled Water album. This cover version is called El Condor Pasa (If I Could).

"The Sound of Silence" is the song that propelled the 1960s folk music duo Simon & Garfunkel to popularity. It was written in February 1964 by Paul Simon in the aftermath of the 1963 assassination of John F. Kennedy. An initial version preferred by the band was remixed and sweetened, and has become known as "the quintessential folk rock release". In the U.S., it was the duo's second most popular hit after "Bridge Over Troubled Water".
The song features Simon on acoustic guitar and both singing. It was originally recorded as an acoustic piece for their first album Wednesday Morning, 3 A.M. in 1964 but on the initiative of the record company's producer, Tom Wilson, it was later overdubbed with drums (Bobby Gregg), electric bass (Bob Bushnell) and electric guitar (Al Gorgoni), all without the knowledge or participation of Simon & Garfunkel and rereleased as a single in September 1965.[3][4] The single reached number one on New Year's Day 1966 and was included in the 1966 album Sounds of Silence.
"The Sound of Silence" was originally called "The Sounds of Silence" and is titled that way on the early albums in which it appeared and on the first single release; only on later compilations was it retitled "The Sound of Silence". Both the singular and the plural appear in the lyrics. In his book Lyrics 1964–2008 Simon has the title in the singular.