To listen to Philip Glass’ 20 piano études is to be taken on a far-reaching journey, as he explores not just his entire stylistic spectrum, but his deep love of the great composers, too. Some of these pieces are, naturally, pure Glass—Étude no. 17 is a gently undulating miniature in the mould of his hit soundtrack to the film The Hours. But Étude no. 1 evokes Beethoven’s melodic inspiration and Étude no. 15’s exotic, Impressionist harmonies recall Debussy’s chiming piano masterpieces. Étude no. 9, meanwhile, is a simple piece of improvisation that’s poignant in its harmonic stasis.