The answer might seem nebulous until you hear this extraordinary Russian pianist in action.
He is a musician of formidable technique (the Rachmaninov and Liszt in the recital's second half made that plenty clear) but his real power lies in his ineffable knack of distilling the message of a work into the simplest possible means. If you like your virtuosos overtly demonstrative, Lugansky is not your man.
In his hands JanáÇcek's In the Mist became a study in open space, from the strange, distant melody that begins the suite to the blunt, ugly statement that bring it to a troubled close.
This is fitful music and Lugansky made no apologies for its unresolved silences and fragments; instead he honoured its magical non-sequiturs and hazy tangents. He brought plain-speaking dignity to Schubert's late Four Impromptus D935, and the cumulative emotional effect of his tiny, acutely-felt nuances was devastating.
Lugansky's playing lingers in your mind so that the soundworld of each work on the programme affected those that follow. The mercurial darkness of JanáÇcek permeated five of Rachmaninov's Etudes-tableaux; Liszt's Les jeux d'eau à la Villa d'Este had a Schubertian clarity - no matter what flurry of notes he was faced with, Lugansky always found a direct way through.
He paced Liszt's transcription of the Liebestod from Wagner's Tristan und Isolde superbly. Two encores: Grieg's sweet Arietta and Rachmaninov's tempestuous Prelude in C minor, Opus 23 No 7.
An unforgettable recital.