Without, the clouds grew thicker and blacker as the storm-centre came closer.  As yet the forces, from whose linking the lightning springs, were held apart, and the silence of nature proclaimed the calm before the storm.  Caswall felt the effect of the gathering electric force.  A sort of wild exultation grew upon him, such as he had sometimes felt just before the breaking of a tropical storm.  As he became conscious of this, he raised his head and caught sight of Mimi.  He was in the grip of an emotion greater than himself; in the mood in which he was he felt the need upon him of doing some desperate deed.  He was now absolutely reckless, and as Mimi was associated with him in the memory which drove him on, he wished that she too should be engaged in this enterprise.  He had no knowledge of the proximity of Lady Arabella, and thought that he was far removed from all he knew and whose interests he shared—­alone with the wild elements, which were being lashed to fury, and with the woman who had struggled with him and vanquished him, and on whom he would shower the full measure of his hate.

The fact was that Edgar Caswall was, if not mad, close to the border-line.  Madness in its first stage—­monomania—­is a lack of proportion.  So long as this is general, it is not always noticeable, for the uninspired onlooker is without the necessary means of comparison.  But in monomania the errant faculty protrudes itself in a way that may not be denied.  It puts aside, obscures, or takes the place of something else—­just as the head of a pin placed before the centre of the iris will block out the whole scope of vision.  The most usual form of monomania has commonly the same beginning as that from which Edgar Caswall suffered—­an over-large idea of self-importance.  Alienists, who study the matter exactly, probably know more of human vanity and its effects than do ordinary men.  Caswall’s mental disturbance was not hard to identify.  Every asylum is full of such cases—­men and women, who, naturally selfish and egotistical, so appraise to themselves their own importance that every other circumstance in life becomes subservient to it.  The disease supplies in itself the material for self-magnification.  When the decadence attacks a nature naturally proud and selfish and vain, and lacking both the aptitude and habit of self-restraint, the development of the disease is more swift, and ranges to farther limits.  It is such persons who become inbued with the idea that they have the attributes of the Almighty—­even that they themselves are the Almighty.

Mimi had a suspicion—­or rather, perhaps, an intuition—­of the true state of things when she heard him speak, and at the same time noticed the abnormal flush on his face, and his rolling eyes.  There was a certain want of fixedness of purpose which she had certainly not noticed before—­a quick, spasmodic utterance which belongs rather to the insane than to those of intellectual equilibrium.  She was a little frightened, not only by his thoughts, but by his staccato way of expressing them.