But the obstacle towards the realisation of their daring plan, is not a material obstacle, nor is it the cowardice that sometimes attacks the bravest; it is a good of a different sort, not less vigorous, but of a more lofty quality, gentle and serene, planted in the heart of Macbeth and called by the name of loyalty, duty, justice, respect for the being of others, human piety. Thus he feels himself thrown at once into confusion by the idea that has flashed before him, so great is the savage desire, which it has set alight in his breast, and such on the other hand the reverence which the other idea inspires into his deeper being, and against which he prepares for a desperate struggle. The supernatural challenge keeps undulating in his mind, now divine, now diabolical: _cannot be ill, cannot be good._ But his wife, in whom the power of desire displays itself as absolute and whose determination of will is rectilinear, knowing not struggle or only struggles speedily and completely suppressed, his wife, is ready to take his place, when he shows his weak side, or at the moments of his vacillation. In the logical clarity of vision that comes to her as the result of the clearness of view with which she contemplates the achievement of her end, she has discovered an element of danger. It is concealed in the "milk of human kindness," circulating in the blood of Macbeth, whereby he would attain to greatness, without staining himself with crime. Having discovered the cause of the weakness, she applies the remedy. This does not consist in making a frontal attack upon his moral consciousness, or by negating it, but in exciting or strengthening the will for action, the will pure and simple, taking pleasure in itself alone, by making it feel the necessity of expressing in action what seems to it to be beautiful and delightful, and by making it ashamed of not knowing how to remain at the level of the desire which it has encouraged, of the plan that it has formed. Macbeth holds back troubled, because, though he is as bold as man can be in facing danger, he yet feels that the deed now required of him would take away from him the very character of man; but for his wife, that deed would make of him more than a man. The sophistry of the will, to the aid of which comes the conquering seduction of desire, exercises its irresistible action and the deed is accomplished.