It is indeed true that, with the manifestation of each thought or feeling, a corresponding decomposition of the brain takes place. But it is equally true that, in a voltaic battery in action, each movement of electric force developed there is attended with a waste of the metal-plates which help to form it. But that waste is not converted into electric fluid. The exact quantity of pure zinc which disappears may be detected in the form of sulphate of zinc. The electricity was _not produced, it was only set in motion_, by the chemical decomposition. Here is the true material analogy of the relation of the brain to the mind. Mind, like electricity, is an imponderable force pervading the universe: and there happen to be known to us certain material arrangements, through which each may be influenced. We cannot, indeed, pursue the analogy beyond this step. Consciousness and electricity have nothing further in common. Their further relations to the dissimilar material arrangements, through which they may be excited or disturbed, are subjects of totally distinct studies, and resolvable into laws which have no affinity, and admit of no comparison. It is singular how early in the history of mankind the belief in the separate existence of the soul developed itself as an instinct of our nature. Timarchus, who was curious on the subject of the demon of Socrates, went to the cave of Trophonius to consult the oracle about it. There, having for a short time inhaled the mephitic vapour, he felt as if he had received a sudden blow on the head, and sank down insensible. Then his head appeared to him to open, and to give issue to his soul into the other world; and an imaginary being seemed to inform him that “the part of the soul engaged in the body, entrammelled in its organization, is the soul as ordinarily understood; but that there is another part or province of the soul which is the daimon. This has a certain control over the bodily soul, and among other offices constitutes conscience.”—“In three months,” the vision added, “you will know more of this.” At the end of three months Timarchus died. LETTER V. TRANCE.—Distinction of esoneural and exoneural mental phenomena—Abnormal relation of the mind and nervous system possible—Insanity—Sleep—Essential nature of Trance—Its alliance with spasmodic seizures—General characters of Trance—Enumeration of its kinds. The time has now arrived for expounding the phenomena of Trance; an acquaintance with which is necessary to enable you to understand the source and nature of the delusions with which I have yet to deal. You have already had glimpses of this condition. Arnod Paole was in a trance in the cemetery of Meduegna—Timarchus was in a trance in the cave of Trophonius. Let me begin by developing certain preliminary conceptions relating to the subject.