Gradually sound began to take hold of him, like a slave who has overcome his master. The sensation of sound presented itself to him continually, not in the form of memory, nor as the suggestion of a composition, but in a disquieting way, like some invisible companion, always at one's side, whispering into one's ears. He was not always able to distinguish between what he actually heard, a noise in the street, for instance, which came to him for the most part with the suggestion of a cadence, which his ear completed as if it had been the first note of a well-known tune, and what he seemed to hear, through noise or silence, in some region outside reality. 'So long as I can distinguish,' he said to himself, 'between the one and the other, I am safe; the danger will be when they become indistinguishable.' He had realised a certain danger, always. He felt that he was a piece of mechanism which was not absolutely to be trusted. There had been something wrong from the beginning; the works did not wear evenly; one part or another was bound to use itself up before its time; and then, well, not even a shock would be needed to set everything out of order: it was only a question of time. He began to watch himself more closely, to watch for the enemy; and now a kind of expectant uneasiness came of itself to suggest otherwise imperceptible pains and troubles of sound. He was always listening, with a frequent precipitation of pulses, to nothing, to something about to come, to the fancy of music. The days dragged, and yet some feverish idea seemed always to be hurrying him along; he was restless whenever his fingers were not on the keys of the piano. One day, at a concert, while he was playing one of Chopin's studies, something in the curve of the music, which he had always seen as a wavy line, going on indefinitely in space, spreading itself out elastically, but without ever forming a pattern, seemed to become almost externally visible, just above the level of the strings on the open top of the piano. It was like grey smoke, forming and unforming as if it boiled up softly out of the pit where the wires were coiled up. It was so distinct that he shut his eyes for a moment, to see if it would be there when he opened them again. It was still there, getting darker in colour, and more distinct. He looked out of the corner of his eyes, to see if the people sitting near him had noticed anything; but the people sitting near him had their eyes fixed on his fingers, from which he seemed, as usual, to be quite detached; they evidently saw nothing. He smiled to himself, half apologetically; the piece had come to an end, and he was bowing to the applause; he walked boldly off the platform.