"I think of jazz as being homage through innovation. Don't quote that as a definition, but it comes pretty close. You don't show respect to Frank Sinatra and his great example by trying to sound exactly like him. You show it by sounding exactly like you, and that's the way jazz has always progressed as an art form."
Kurt Elling - who took on Ol' Blue Eyes' 1957 Oscar-winner All The Way at the Jazz Voice concert - has pushed forward the art of jazz singing more than any other male performer of his generation.
The Chicagoan is probably credited single-handed with reviving the form and taking up the mantle of the great Mark Murphy – the singer he perhaps most closely resembles – and all the others going back to Sinatra, Joe Williams, Johnny Hartman, Nat Cole and Louis Armstrong, whose singing is decried by so-called purists but was every bit as influential as his trumpet playing.
Elling's arrival on the scene was almost as unusual as his chosen instrument. The son of a Lutheran Kapellmeister, who also worked as a high-school band instructor and kept a batch of Sinatra records alongside his sacred music score, the young man sent a demo tape of his singing to the reviving Blue Note label and, almost uniquely, was lifted from the slush pile and signed.
A string of classic albums followed, Close Your Eyes, The Messenger, Live In Chicago, Flirting With Twilight, the peerless Man In The Air, marked by a highly eclectic choice of material from settings of poetry by Rainer Maria Rilke, Walt Whitman, Theodore Roethke and Sufi master Rumi, to pop material by Argent and jazz repertory. He's also largely responsible for reviving vocalese, the once-fashionable practice of fitting lyrics to famous jazz solos.
"I remember seeing Tony Bennett on television. He was the only guy in the orchestra who was wearing a white tux and I thought, 'That would be good. To be the only man on stage in a white jacket'."
And yet, Elling's extraordinary art is very much concerned with the sound of the band and how the singer fits into the ensemble: "Yes, singing a song is not just about delivering the lyric effectively. It's about how the music functions and how every single member of the band functions in the music.
"Sometimes, with vocalese, I'm dealing with something, a great solo from the past, which is so iconic I can't presume to change it or mess with it.
"So what I have to do is make the words and the way the words fall and convey meaning take on something new. That's my homage. Making it different to Frank Sinatra or to Lester Young, or Charlie Parker."
And one might add Cab Calloway to that, a performer so idiosyncratic almost any latter-day version of Minnie The Moocher seems fated to anti-climax.
And yet Elling's approach avoids that trap entirely by reinventing the song rather than subverting. Fidelity to the original is the first step towards originality.
Elling explains: "I don't do it on paper. I do it all with the ears and the ears have had some pretty good training. When you start out learning Bach motets and you're singing soprano [treble] to begin with, then alto, then tenor, then maybe bass, you're hearing that piece from all sorts of angles.
"That kind of study goes in and stays in. I guess when I listen to Sinatra, I hear him on different levels, and some of those feed into what I go out and sing."