An inkling of the true state of the case began to dawn upon him, and he was on the verge of entering—­indeed, his hand already touched the door-knob—­when his eye, still glued to the spy-hole, detected a slight movement.  Directly opposite, between him and the fireplace, something stirred.  He watched very attentively and made certain that he was not mistaken.  An object on the mantelpiece—­it was a blue vase—­disappeared from view.  It passed out of sight together with the portion of the marble mantelpiece on which it rested.  Next, that part of the fire and grate and brass fender immediately below it vanished entirely, as though a slice had been taken clean out of them.

Dr. Silence then understood that something between him and these objects was slowly coming into being, something that concealed them and obstructed his vision by inserting itself in the line of sight between them and himself.

He quietly awaited further results before going in.

First he saw a thin perpendicular line tracing itself from just above the height of the clock and continuing downwards till it reached the woolly fire-mat.  This line grew wider, broadened, grew solid.  It was no shadow; it was something substantial.  It defined itself more and more.  Then suddenly, at the top of the line, and about on a level with the face of the clock, he saw a round luminous disc gazing steadily at him.  It was a human eye, looking straight into his own, pressed there against the spy-hole.  And it was bright with intelligence.  Dr. Silence held his breath for a moment—­and stared back at it.

Then, like some one moving out of deep shadow into light, he saw the figure of a man come sliding sideways into view, a whitish face following the eye, and the perpendicular line he had first observed broadening out and developing into the complete figure of a human being.  It was the patient.  He had apparently been standing there in front of the fire all the time.  A second eye had followed the first, and both of them stared steadily at the spy-hole, sharply concentrated, yet with a sly twinkle of humour and amusement that made it impossible for the doctor to maintain his position any longer.

He opened the door and went in quickly.  As he did so he noticed for the first time the sound of a German band coming in gaily through the open ventilators.  In some intuitive, unaccountable fashion the music connected itself with the patient he was about to interview.  This sort of prevision was not unfamiliar to him.  It always explained itself later.

The man, he saw, was of middle age and of very ordinary appearance; so ordinary, in fact, that he was difficult to describe—­his only peculiarity being his extreme thinness.  Pleasant—­that is, good—­vibrations issued from his atmosphere and met Dr. Silence as he advanced to greet him, yet vibrations alive with currents and discharges betraying the perturbed and disordered condition of his mind and brain.  There was evidently something wholly out of the usual in the state of his thoughts.  Yet, though strange, it was not altogether distressing; it was not the impression that the broken and violent atmosphere of the insane produces upon the mind.  Dr. Silence realised in a flash that here was a case of absorbing interest that might require all his powers to handle properly.