“Put your ass in it there!”

This blunt command may just be the most remarkable example of jazz education ever captured on tape. It was recorded on a boat anchored in Copenhagen Harbor in October 1970, when the legendary tenor saxophonist Ben Webster was invited to perform with the Danish Radio Jazz Orchestra. Webster was actually brought in strictly as a guest soloist, but as it happened, the group was playing one of his own tunes (“Did You Call Her Today,” a variation on Duke Ellington’s “In a Mellotone,” which itself was based on “Rose Room”), and the conductor, Niels Jørgen Steen, was an old friend. Thus, it seemed natural for Webster to take to the podium and coach the 20 or so young Danes, not only in how he wanted his music played, but in jazz phrasing and feeling in general.

With no apparent idea that the tape machines were running, Webster (1909–73) delivered a brilliant and unexpurgated document of a jazz master in action — not in performance, but in communication with younger artists, in the explanation and demonstration of his musical philosophy. It’s the highlight, in fact, of “Dig Ben!” a new eight-disc box set from the Danish label Storyville Records. Webster is most concerned with dynamics and rhythmic nuances. He points out that the two factors that make the music swing are the louds and softs, and knowing exactly how and when to cut them off. “Hold that note — it’s not ‘wap,’ it’s more like ‘WHOOOP!'” he tells one of the young musicians. “Cut it off, like you’re eatin’ fried chicken, WHOOOP! or you bust out laughin,’ WHOOOP! Scream it, but cut it off!” Webster bellows each one of those “whoops” in a manner that seems as close as human speech can come to one of his transcendent tenor solos.

As with some of Webster’s faster solo statements, in which he gets almost hysterical, he nearly gets carried away here: “[It’s] too soft,” he shouts. “You’re going all Guy Lombardo there! Hit them notes on that [chord] change. Punch it, like Joe Louis! BAM!! Scream it! Scream that sh–!”

At another point, Webster begins to apologize to Steen before launching into a set of fanciful metaphors. “Steen, pardon me for f—ing over your music, but there’s syrup in there. When a bee sting you, he die, but he leaves the stinger in you!” It’s hard to know exactly what he’s talking about, but his meaning, in terms of how he feels the music is supposed to sound, is crystal clear. “No fool, no fun,” he says repeatedly; take a chance with the music, put your whole body and soul into it — even your posterior.

In general, Webster gives the Danish musicians the kind of tough love he’d been dispensing both to listeners and fellow jazzmen for nearly 40 years by 1970. As a budding musician in Kansas City, he’d originally studied violin, which, according Frank Buchman-Moller, who wrote most the notes for the Storyville booklet, contributed to his glissando-driven approach to a ballad, some remarkable examples of which are included in the new box.

Already an accomplished musician, Webster studied and worked with Billy Young, alongside the professor-bandleader’s son, Lester (both were born in 1909), in the late 1920s. As the ’30s began, Webster, based in Kansas City and then New York, played in every major black band that existed — Fletcher Henderson, Benny Carter, Andy Kirk, Cab Calloway, Bennie Moten (side-by-side with Count Basie) — before reaching the upper brackets of jazz immortality by playing a featured role with the greatest composer-bandleader of them all, Duke Ellington. For 3 1/2 years, Webster was a major star with that Olympian ensemble and was the force behind such Ellington masterpieces as “Cottontail” and “All Too Soon.” In fact, even if Webster’s career had been as tragically short as that of his bandmate, the pioneering bass soloist Jimmy Blanton, he still would be regarded as a titan of the tenor sax.

According to another of the booklet’s annotators, Henrik Iversen, Webster left Ellington’s employ for the same reason he later wound up spending the last decade of his life in Europe: He dreaded airplanes, and by 1943, the Ellington band was flying to as many gigs as it was riding to. Rather than be forced to fly regularly, Webster exited the band. Twenty years later, when he forced himself to make the trip to London for an engagement at Ronnie Scott’s (also sampled in the box), he decided to stay in Europe rather than risk the trip home. As his bassist, Bo Stief, recalls in the notes to the box set, “I had the impression there were things he’d fled from over in the states that he couldn’t return to.”

Indeed, Webster looks pugnacious on all of his album covers, brimming over with bad attitude, daring onlookers to take a piece of him. Another anecdote recalls how he repeatedly tried to take on heavyweight Joe Louis in a street brawl. Yet Webster was terrified of the sky and the sea and would only travel on dry land. Ironically, his music was all about heights and depths, the soaring rapture he expressed in slow ballads versus the exuberant, euphoric rapture of a barn burner like “Cottontail,” and the blues he could play at any speed. (In this, he had a considerable edge over his original inspiration, Coleman Hawkins, who was never much of a bluesman.) One of Webster’s most frightening performances in that form is here: “Poutin'” from a 1959 session with the brilliant pianist Jimmy Rowles, a blues so minor it’s positively evil.

With a couple of exceptions, the music on “Dig Ben!” springs from Webster’s 10-year stay in Europe, mostly from Denmark and Sweden. There are some brilliant encounters with fellow American stars traveling abroad, such as the pianist Teddy Wilson, trumpeters Buck Clayton and Clark Terry, and fellow tenor giant Dexter Gordon. There are several sessions with local orchestras as well, such as a haunting reading of “Greensleeves” with strings and a reading of “Cry Me a River,” with the same Danish Radio Orchestra, which positively weeps. Webster serves up plenty of heat on “Baby, It’s Cold Outside,” delivered as a duet with the black female singer Matty Peters, on which he plays the usual male part on his tenor with a voice that says much more than any human throat ever could.

In that 1970 rehearsal, which jazz pedagogues such as the fine pianist, Dick Katz, have played for their students, Webster exhorts the Danish musicians to play a particular phrase as if it were “the last breath in life.” That’s the way Webster played every song — as if it were to be his last. He put more than his ass in every number, he puts in them his body and heart and soul and everything else.

wfriedwald@nysun.com