I agree Sound Of Silence is an amazing song.
Also songs like the Boxer and Bridge Over Troubled Waters are some of the best songs of all time.

I was just listening to the country song When You Say Nothing At All.
The version done by Alison Krauss
Wow, what a beautiful song.

Lines like
It's amazing how you can speak right to my heart
with out saying a word you can light up the dark
Or
Old mister Webstor could never define
what's being said between you're heart and mine
Combined with that beautiful simple melody
That song still brings on chills every time I listen to it.

Tim