But he had not thought of the possibility that, if this proved true some day, the truth might come in a sinister shape. The two things that had taken him utterly by surprise in the matter of his feeling towards Mabel Manderson were the insane suddenness of its uprising in full strength and its extravagant hopelessness. Before it came, he had been much disposed to laugh at the permanence of unrequited passion as a generous boyish delusion. He knew now that he had been wrong, and he was living bitterly in the knowledge. Before the eye of his fancy the woman always came just as she was when he had first had sight of her, with the gesture which he had surprised as he walked past unseen on the edge of the cliff; that great gesture of passionate joy in her new liberty which had told him more plainly than speech that her widowhood was a release from torment, and had confirmed with terrible force the suspicion, active in his mind before, that it was her passport to happiness with a man whom she loved. He could not with certainty name to himself the moment when he had first suspected that it might be so. The seed of the thought must have been sown, he believed, at his first meeting with Marlowe; his mind would have noted automatically that such evident strength and grace, with the sort of looks and manners that the tall young man possessed, might go far with any woman of unfixed affections. And the connection of this with what Mr. Cupples had told him of the Mandersons’ married life must have formed itself in the unconscious depths of his mind. Certainly it had presented itself as an already established thing when he began, after satisfying himself of the identity of the murderer, to cast about for the motive of the crime. Motive, motive! How desperately he had sought for another, turning his back upon that grim thought, that Marlowe—obsessed by passion like himself, and privy perhaps to maddening truths about the wife’s unhappiness—had taken a leaf, the guiltiest, from the book of Bothwell. But in all his investigations at the time, in all his broodings on the matter afterwards, he had been able to discover nothing that could prompt Marlowe to such a deed—nothing but that temptation, the whole strength of which he could not know, but which if it had existed must have pressed urgently upon a bold spirit in which scruple had been somehow paralysed. If he could trust his senses at all, the young man was neither insane nor by nature evil. But that could not clear him. Murder for a woman’s sake, he thought, was not a rare crime, Heaven knew! If the modern feebleness of impulse in the comfortable classes, and their respect for the modern apparatus of detection, had made it rare among them, it was yet far from impossible. It only needed a man of equal daring and intelligence, his soul drugged with the vapours of an intoxicating intrigue, to plan and perform such a deed.