The band walked into the Meddle sessions in 1971 with no songs ready and a record contract waiting. What followed was the sound of a group figuring out who it was about to become. The first side is restless and uneven on purpose: a blues workout, a folk sketch, a near-instrumental built on one bassline, a quiet song for a dog. Pleasant, scattered, the work of a band still trying things. Then you turn it over.

Side two is one track. Echoes fills all of it, twenty-three minutes that rise, drift somewhere genuinely odd, and rise again. It is the moment the four of them stopped being a promising psychedelic act and started building the patient, architectural music they would be known for. Two years before the album everyone can name, the blueprint is already sitting here on the second side. Meddle is where Pink Floyd quietly worked it out.