"Wish you were here" by Pink Floyd, 1975.
One of Manel's favorite songs, that we shared in his Memorial at Les Corts.
Lyrics (available at same link --YouTube)
So, so you think you can tell
Heaven from Hell,
Blue skys from pain.
Can you tell a green field
From a cold steel rail?
A smile from a veil?
Do you think you can tell?
.....