Page:Popular Science Monthly Volume 30.djvu/688

666 more pronounced expressions of lunacy, but are unable to trace the expressions to their relating causes.

To have even a moderate understanding of insanity, it is necessary to clearly comprehend the nature and import of "illusion," "hallucination," and "delusion"—which, when they exist, are of so much importance that some would fain have us believe that the possession of any one of these symptoms is sufficient to make genius and insanity "a little more than kin, and less than kind."

When a person sees, hears, smells, tastes, or feels an object, but perceives it to be what it is not—as when a tree becomes a man, and the murmuring wind his voice—an illusion exists; a real sense-impression is wrongly interpreted by the perceptive centers, and hence the perception does not correspond with the external object.

Hallucination originates within the brain, and is the perception of that which has no real existence; indeed, so purely subjective is it, that the senses have no agency in its production. Under conditions of concentrated attention, ideas, feelings, and sense-perceptions, are marshaled into consciousness with as great distinctness as if they were the products of external objects, rather than that of subjective conditions alone. This comes from the fact that the sense-centers are influenced by impressions received independent of their source. Its function is to transform impressions into conscious sensations, and hence an idea or emotion, when directed in a special way with persistent, concentrated force, may so impress the sensorium as to cause it to project into consciousness sensations which seem to come from objects in the external world. I can not tell how this is done, neither can I tell how it is done when impressions come from without. The facts we know, but the secrets of transformation elude us. The brain constructs new forms, but conceals the methods of imagination by the shadow of unconsciousness.

Ajax becomes enraged because the arms of Achilles are given to Ulysses, and in his wrath he sees animals as Greeks and assails them as if Ulysses and Agamemnon themselves were before him. Talma intensified his emotions and his dramatic effect by the illusive specters of his mind. Spinoza beheld with great distinctness the disagreeable image of his dream a long time after sleep was gone; and Niebuhr, when describing the scenes of his travels, would see all rise before him in "all the coloring, animation, and splendor of Nature." Multitudes have been at times subject to the same false perceptions; as when the soldiers under Constantine saw the cross in the sky bearing the inscribed words, "In hoc signo vinces"; or when the army at the battle of Antioch, excited and superstitious, saw the saints—George, Demetrius, and Theodosius—descending through the clouds of heaven to their support.

The consummate skill of Shakespeare in portraying the different phases of false perception, and his power of psychological analysis, are