Folk singer Paul Simon remembered the attacks of Sept. 11, 2001 by singing the song that first propelled the duo Simon & Garfunkel into popularity.
Simon wrote "The Sound of Silence" in 1964, a year after the 1963 assassination of President John F. Kennedy.
The song took on a different meaning at 10:41 a.m. ET Sunday as Simon performed it at Ground Zero.
"Hello darkness, my old friend / I've come to talk with you again"
In their first 2001 episode after the 9/11 attacks, Simon had performed "The Boxer" on NBC's Saturday Night Live.