[Rubinstein] launched out almost without a breath into Beethoven's great Sonata Appassionata — Op. 57.

 The scene changed now, with a vengeance. There came tremendous rushes and bursts, given with a swaying power, a marvellous clearness, a rapid surging and seething and subsiding, which absolutely electrified the crowd of listeners. (Manns glowed over these orchestral effects — as well he might.) The slow movement glided its way like a gentle river, every shade of it rendered with the most loving observance, and the most poetic feeling. Then came the most stormy finale. Towards the close of this, he was simply like some inspired thing, struggling (and visibly, with every muscle of his body) as with a contending demon, till at the close, with a mighty grasp and shove, he bound him down and held him subservient to his will.

This rather fanciful language does, I assure you, convey quite what it was like to me.