What makes a track a classic?

Its that feeling you get once the beat fades out. Me personally it is when you hear a song and instantly know it is gonna withstand the test of time. The song will touch your soul and you feel it, I mean really feel it. Mostly for me it will be something you can relate to a particular time in your life. When ever you hear that song t envokes that feeling you had when you first heard it. It doesnt happen that often but when it does you know instantly. The beat has to bring about some sort of emotion and the lyrics must do the same also.