If anyone asks you what bop is, hand them this album, Sphere On Tour, with confidence. Universally recognised as one of the finest quartets in the history of jazz, and originally formed as a tribute to Monk’s musical aesthetic, Sphere glide through harmonic and melodic patterns with the ease of those who have mastered every aspect of the form and know how to channel it into the soul.

On Tour is, in fact, the album one would recommend to an alien asking where to start to understand what bop is.

He would thus encounter at least four ‘aliens’: Charlie Rouse, Kenny Barron, Buster Williams and Ben Riley are, together, the litmus test of what distinguishes a band from a collective. Here there is no mere craftsmanship, but rather a passionate urgency to share thoughts through the language of the beat; space is the extension of sound and time is the pulse of the ride and the hi-hat. Of course, the fifth ‘alien’ in the background remains Thelonious Monk, to whom Rouse and Riley dedicate a blisteringly fast version of Well You Needn’t at the end.