They would perfect this on Dark Side of the Moon . But in 1969, they proved they had the ambition . Grade: B+ (Essential for deep fans, confounding for casuals)

Immaculate. The versions of “Astronomy Domine,” “Careful with That Axe, Eugene,” and “Set the Controls for the Heart of the Sun” are definitive. You hear the space between the notes. You hear the echo. This is the Floyd as a unit —meditative, powerful, and scary.

If 1967 was Pink Floyd’s psychedelic birth and 1968 their desperate scramble to survive the departure of Syd Barrett, then 1969 was the year they stopped treading water and began building their cathedral. It wasn't their most famous year, nor their most commercially successful, but 1969 is the dark, fascinating blueprint for everything that would make them legends.

In 1969, Pink Floyd stopped imitating Syd Barrett and started becoming the machine. The machine was rusty, it leaked oil, and it occasionally made no sense. But when it fired up—on “Careful with That Axe, Eugene” or “The Narrow Way”—you could hear the future breathing.