In all animals the living brain is essential to all phases of thought. The thought-ability of any animal is always in precise proportion to the perfection and activity of the brain. The power of developing thought grows, diminishes, and ceases, the cessation always being complete when the brain ceases to perform its vital functions. If the brain is injured the thought-ability is impaired, the thinking deranged. Yet who to-day would think it wise or necessary, with evidence of aberration of thought resulting from local injury, to treat it as a case of demoniacal possession? One other difficulty in the discussion of this question is that new discoveries are not taken into account by our spiritual antagonists in estimating the value of old formulas. Two thousand three hundred years ago demonology had not yet passed into the region of fable. Socrates spoke of the soul as if it had been specially infused into the body by the Gods, and declared “that the soul which resides in thy body can govern it at pleasure;” but such discoveries have since been made in physiology and psychology that were Socrates alive to-day Aristodemus might now well make answers to the old Greek sage which were then impossible. Plato, too, contended for the immortality of the human soul, but under cover of this line of reasoning he also offered proof that the world was an animal and had a like soul. Plato’s orthodox admirers today carefully avoid Plato’s presentation of the earth as an animal with an immortal soul. David Masson attributes to Auguste Comte the first open and clear adoption of a position on the soul question which rendered evasion difficult. “Previous physiological psychologists, including phrenologists, had generally shrunk from the extreme to which their opponents had said they were committed. They had kept up the time-honored distinction between mind and body; they had used language implying a recognition of some unknown anima, or vital principle, concealed behind the animal organism; some of them had even been anxious to vindicate their belief in the immateriality or transcendental nature of this principle. But Comte ended all that shilly-shallying. Mind, he said, is the name for the functions of brain and nerve; mind is brain and nerve. This destroyed, that ceases.”