combustion, the action of a morbidly-irritable group of cells may be said to resemble an explosion, and one, too, which is both violent and persistent. With the stimulus there flames forth in consciousness a presentation, or train of presentations, conceptions and reasonings, which suffuse the mind as with the glare of a conflagration, outshining all other ideas. The degree of exclusiveness and insistence in the predominance of any presentation is in proportion to the degree of morbid irritability in the particular tract of brain by which it is elaborated. Where the degree is not excessive there arise obsessions which the consciousness recognises as morbid. They do not preclude the coexistence of healthy functioning of the brain, and consciousness acquires the habit of treating these co-existent obsessions as foreign to itself, and of banishing them from its presentations and judgments. In aggravated cases these obsessions grow into fixed ideas. The immoderately excitable portions of the brain work out their ideas with such liveliness that consciousness is filled with them, and can no longer distinguish them from such as are the result of sense-impressions, the nature and strength of which they accurately reflect. Then we reach the stage of hallucinations and delirium. Finally, in the last stage, comes ecstasy, which Ribot calls ‘the acute form of the effort after unity of consciousness.’ In ecstasy the excited part of the brain works with such violence that it suppresses the functioning of all the rest of the brain. The ecstatic subject is completely insensible to external stimuli. There is no perception, no representation, no grouping of presentations into concepts, and of concepts into judgments and reasoning. A single presentation, or group of presentations, fills up consciousness. These presentations are of extreme distinctness and clearness. Consciousness is, as it were, flooded with the blinding light of mid-day. There therefore takes place exactly the reverse of what has been noticed in the case of the ordinary mystic. The ecstatic state is associated with extremely intense emotions, in which the highest bliss is mixed with pain. These emotions accompany every strong and excessive functioning of the nerve-cells, every extraordinary and violent decomposition of nerve-nutriment. The feeling of voluptuousness is an example of the phenomena accompanying extraordinary decompositions in a nerve-cell. In healthy persons the sexual nerve-centres are the only ones which, conformably with their functions, are so differentiated and so adapted that they exercise no uniform or lasting activity, but, for by far the greatest part of the time, are perfectly tranquil, storing up large quantities of nutriment in order, during very short periods, to decompose this suddenly and, as it were, explosively. Every nerve-centre which operates in this way would procure us voluptuous emotion; but precisely among healthy