It's how you remix. You take existing songs, you chop them up, you transform the pieces, you combine them back together again, and you've got a new song, but that new song is clearly comprised of old songs.
Assim se faz o remix. Pegamos músicas já existentes, as dividimos em partes, transformamos as peças, as combinamos novamente, e temos uma música nova, mas esta é distintamente composta de músicas antigas.