The worst apprehensions felt by the doctor for the patient were soon realized.  The fever flew to his brain.  For nearly six weeks he lay prostrate, at the mercy of death; now raging with the wild strength of delirium, and now sunk in the speechless, motionless, sleepless exhaustion which was his only repose.  At last; the blessed day came when he enjoyed his first sleep, and when the doctor began, for the first time, to talk of the future with hope.  Even then, however, the same terrible peculiarity marked his light dreams which had previously shown itself in his fierce delirium.  From the faintly uttered, broken phrases which dropped from him when he slept, as from the wild words which burst from him when his senses were deranged, the one sad discovery inevitably resulted—­that his mind was still haunted, day and night, hour after hour, by the figure in the yellow mask.

As his bodily health improved, the doctor in attendance on him grew more and more anxious as to the state of his mind.  There was no appearance of any positive derangement of intellect, but there was a mental depression—­an unaltering, invincible prostration, produced by his absolute belief in the reality of the dreadful vision that he had seen at the masked ball—­which suggested to the physician the gravest doubts about the case.  He saw with dismay that the patient showed no anxiety, as he got stronger, except on one subject.  He was eagerly desirous of seeing Nanina every day by his bedside; but, as soon as he was assured that his wish should be faithfully complied with, he seemed to care for nothing more.  Even when they proposed, in the hope of rousing him to an exhibition of something like pleasure, that the girl should read to him for an hour every day out of one of his favorite books, he only showed a languid satisfaction.  Weeks passed away, and still, do what they would, they could not make him so much as smile.

One day Nanina had begun to read to him as usual, but had not proceeded far before Marta Angrisani informed her that he had fallen into a doze.  She ceased with a sigh, and sat looking at him sadly, as he lay near her, faint and pale and mournful in his sleep—­miserably altered from what he was when she first knew him.  It had been a hard trial to watch by his bedside in the terrible time of his delirium; but it was a harder trial still to look at him now, and to feel less and less hopeful with each succeeding day.

While her eyes and thoughts were still compassionately fixed on him, the door of the bedroom opened, and the doctor came in, followed by Andrea D’Arbino, whose share in the strange adventure with the Yellow Mask caused him to feel a special interest in Fabio’s progress toward recovery.

“Asleep, I see; and sighing in his sleep,” said the doctor, going to the bedside.  “The grand difficulty with him,” he continued, turning to D’Arbino, “remains precisely what it was.  I have hardly left a single means untried of rousing him from that fatal depression; yet, for the last fortnight, he has not advanced a single step.  It is impossible to shake his conviction of the reality of that face which he saw (or rather which he thinks he saw) when the yellow mask was removed; and, as long as he persists in his own shocking view of the case, so long he will lie there, getting better, no doubt, as to his body, but worse as to his mind.”