Otis Blue/Otis Redding Sings Soul is one of the great albums of Rhythm and Blues. It’s probably bad form to frontload a music review with such a strong statement, but any other approach would feel disingenuous.

First, it’s an Otis Redding record. In and of itself this is a guarantee of quality. Redding’s vocals provide a master class in soul interpretation, and they maximize the emotional impact of every syllable. Otis Blue is no exception to the rule. On ballads like “I’ve Been Loving You Too Long” Redding’s delivery practically drips with desperation. His up-tempo performances are equally adept—Redding’s voice forcefully propelling songs like “Shake” and “Respect”. Throughout Otis Blue, Redding’s vocals are authoritative.

Second, the backing band on Otis Blue is phenomenal. Although the original liner notes provide little information about the musicians on the session, Otis Blue features members Booker T. & The MG’s, the Mar-Keys, and the Memphis Horns. The album may be called Otis Blue, but the results are red hot. Fluent in all things soul, the band absolutely cooks on funky numbers like “Down in the Valley” and provides a graceful eloquence to support Redding on the album’s tender ballads. Throughout, the arrangements are economical—no clutter, no wasted notes. The songs are stripped to their emotional core and played for all they are worth.

Yet, Otis Blue’s status as a benchmark album is grounded in more than the musicianship. After all, great vocals and a crack band define every other Otis Redding album. The real difference is to be found in the album’s impeccable material.

Perhaps more than any other soul record, Otis Blue is a veritable Rosetta Stone of the music of the 1960s. Otis Blue seamlessly translates Motown, rock, and blues into the musical vernacular of Memphis soul through a handful of well-chosen covers. On “Satisfaction” Redding takes the Rolling Stones classic to its logical conclusion, considering that the Stones had written the track with Redding in mind. Here he rocks it harder than the original, on top of a pounding bass figure and a persistently punchy horn line. Redding and the band turn in a stripped down and gritty performance on the sometimes-saccharine Motown classic “My Girl”, tersely illustrating the difference in sounds between Detroit and Memphis. The close relationship between electric blues and soul music is apparent in “Rock Me Baby” with Redding and the band romping through the B.B. King standard with sultry aplomb.

Otis Blue also neatly summarizes the soul music that had preceded it. In addition to three excellent Sam Cooke covers, and the smoking version of Solomon Burke’s “Down in the Valley”, Otis Blue features a stunning rendition of William Bell’s “You Don’t Miss Your Water”. Bell’s version of that classic ballad had helped define the sound of Memphis soul and gave Stax Records an early hit only four years earlier.

But, like all truly great albums, Otis Blue does more than summarize the past—it captures a moment. Here, it’s largely thanks to Redding’s original compositions. For example, “I’ve Been Loving you too Long” is a synthesis of mid-sixties soul at its very best, characterized by emotional vulnerability, but never maudlin.

These attributes are surely enough to cement Otis Blue’s status, but the album has one more trick: its material also foreshadowed the future of soul music. In 1966, Atlantic Records signed a promising singer and pianist named Aretha Franklin to their roster. Her previous record deal with Columbia had yielded a string of albums that had largely failed to connect with the public. On Atlantic her luck would change with a long string of seminal rhythm and blues hits. Among the first was a cover of one of Redding’s originals from Otis Blue, “Respect”. Franklin’s new version would take soul music to new heights, topping Billboard’s pop and R&B charts in 1967.

It makes sense that Franklin and Atlantic would have turned to Otis Blue for material. For all of its musicality and historical importance, Otis Blue is also an infectiously fun record.