his brain. Absorbed on what is going on within, he cannot, or will not, give attention to anything else which might tend to dispel the fascination.1 Hence, in all probability, the change of scene that is commonly recommended in such cases acts in the way of serving to recall his thoughts to what is going on around him. There seems even reason to believe that if the eye were well trained and duly exercised it would tend, in many cases, to prevent insanity.

The eye has a wonderful power in lighting up and animating the countenance, and reflects in a large degree what is passing in the mind. Every passion of the mind has its appropriate expression in the eye, which sometimes speaks with a power and an eloquence that cannot be equalled even by the lips.2

The sense of sight is capable of extraordinary improvement by education, and that in the way either of increased quickness or readiness in the perception of objects generally, or in the power of discerning bodies of extreme minuteness, and in discriminating the slightest shades of difference in form, size, colour, &c.3

"In a general way in persons with hallucinations . . . the phenomena of the external world no longer produce in the sensorium anything more than an abortive impression. The patient, thus shut up from external sounds, a stranger to everything that passes around him, lends but an inattentive ear to the things of the external world. He lives, as people say, in himself, upon remembrances of the past, and upon his habitual delirious conceptions.”—J. Luys.

2 "It is chiefly the eye which betrays in our face the state of our mind and thoughts; and this is done for the most part by the movement and position of the eyeball, associated with which are, of course, the action of the facial muscles, of the eyelids, as well as the power possessed by the eye of accommodating itself to a change of circumstance. A troubled look lowers the eyes, an animated one raises them; and thus the mind, while it derives mental nourishment from without through the eye, reveals its inner actions through the same organ."-Prof. Bernstein.

"The sense of vision may vary in its degree of perfection, as re

The exercise of the sight in one direction, or on one class of objects, does not of necessity improve or strengthen it in other directions, or for other classes of objects. In each case there is developed a certain readiness or aptitude for noting appearances, or minute shades of difference, of particular kinds, which pass unnoticed by those who have not been accustomed to observe the same kind of phenomena. It is by the habitual direction of our attention to the effects produced upon our consciousness by the impressions made upon the eye and transmitted to the sensorium that our sight, like our other senses, is trained. (See "Attention ".)

gards either the faculty of adjustments to different distances, the power of distinguishing accurately the particles of the retina affected, sensibility to light and darkness, or the perception of the different shades of colour."-Dr. Kirkes.

"The microscopist, who is constantly on the outlook for the various forms of organic structure with which his mind is familiar, discerns these without difficulty or hesitation where an ordinary observer sees nothing but a confused jumble of tissue."-Dr. Carpenter.

CHAPTER V.

MENTAL IMAGES.

"After an object is removed or the eye shut, we still retain an image of the thing seen, though more obscure than when we saw it; and this it is the Latins call imagination, and apply the same. to all the other senses. But the Greeks call it fancy (Phantasia), which signifies appearance.”—Malebranche.

Aristotle maintains "that of every object of thought there must be in the mind some form, phantasm, or species; that things sensible are perceived and remembered by means of sensible phantasms, and things intelligible by intelligible phantasms; and that these phantasms have the form of the object without the matter, as the impression of a seal upon wax has the form of a seal without its matter".-Lord Kames.

"The word image is borrowed from the history of vision; strictly, it only denotes the cerebral revival of the optical sensation; it is by extension that we have applied the same name to the cerebral revival of muscular and tactile sensation, of sensations of sound, taste, and smell."-H. Taine.

"The word image must be understood as designating any recalled feeling of whatever kind which wants something of the signature and energy of the feeling or after-feeling it recalls. It may be a sight, a sound, a taste, a touch, a pain, an effort, a terror, a word."-G. H. Lewes.

We may define an image, then, as "a repetition or revival of the sensation, while at the same time we distinguish it from the sensation," among other things "by its origin, since it has the sensation as its antecedent, while the sensation is preceded by an excitation of the nerve ".-H. Taine.

"Sensation and after-sensation have their origin in an objective stimulus, the image has its stimulation from within."-G. H. Lewes.

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That which constitutes recollection or an act of memory is the present image which a past sensation has left in us, an image which... seems to us the sensation itself."-H. Taine.

THE

HF physical motion or change which occasions a sensation must be apprehended by the mind before it can be perceived or become an object of consciousness. Impressions are, doubtless, being constantly made upon the senses, and their influence conveyed to the brain, that never come within the range of consciousness, because the mind fails to apprehend them.

In order that a sensation may be taken up and perceived by the mind, it is necessary that an image of it be formed. The mind can take no account of the physical movements or changes that may be taking place in the body, except in so far as they give rise to mental images.1 It can perceive nothing, understand nothing, remember nothing but images.3

We use the term "mental image" in preference to the corresponding word "idea," employed by Locke and others, in consequence of the frequent vagueness and indefiniteness of the latter. A mental image may be said to be the mental side of a physical change or

"It is the mental not the bodily impression that constitutes the actual perception."-Dr. Carpenter.

Is not thought "principally a calling up and arranging before us of the images of physical things which have been given us through sense?... Even in thinking of moral and abstract subjects, we shall find that they present themselves to us embodied in somewhat of a sensuous or physical garb, and at least always with distinct time and space properties, for these are essential elements of human thought."-R. S. Wyld. "To recollect, to imagine, to think, is.. to call up the more or less enfeebled and transformed visual images of things. In all the higher operations we affect by means of abstract names-judgment, reasoning, abstraction, generalisation, combination of ideas-there are images more or less effaced or more or less distinct."-H. Taine. "Locke holds that we cannot perceive, remember, nor imagine anything but by having an idea or image of it in the mind."-Lord Kames. "Nothing is remembered but through its idea.”—Jas. Mill.

3 "The word 'idea' being that term which I think serves best to stand for whatsoever is the object of the understanding when a man thinks, I have used it to express whatever is meant by phantasm, notion, species, or whatever it is which the mind can be employed about in thinking.”—John Locke. “The word 'idea,' as one prostituted to all meanings, it were perhaps better altogether to discard. As for the representations of the imagination, or phantasy, I would employ the terms image or phantasm, it being distinctly understood that these terms are applied to denote the representations, not of our visible perceptions merely as the terms taken literally would indicate, but of our sensible perceptions in general.”—Sir W. Hamilton.

condition of body-a mental representation, or a representation to the mind of a physical fact. In sensation, as we have seen, all that passes from the organ of sense to the brain is a form of motion. The senseorgan is acted upon by an external object, and a form of motion is set up which is conveyed to the brain, and from the different kinds of motion so conveyed the mind constructs images to itself of all the vast variety of qualities or properties that we commonly attribute to external objects.1

These images grow and acquire strength and clearness by slow degrees. To the opening mind of the child the beautiful landscape or the lovely flower presents only vague patches of colour. But by degrees, as the same sensations are repeated, the mind comes to distinguish the different parts, and the images formed of them in the mind become more distinct and clear.

1 "The impression on the nerve can have no resemblance to the ideas suggested in the mind. All that we can say is that the agitations of the nerves of the outward senses are the signals which the Author of Nature has made the means of correspondence with the realities. There is no more resemblance between the impressions on the senses, and the ideas excited by them, than there is between the sound and the conception raised in the mind of that man who, looking out on a dark and stormy sea, hears the report of a cannon, which conveys to him the idea of despair and shipwreck."-Sir C.

Bell

2"The eye learns to discriminate colours and shades of colour where at first there was only a vague blur of feeling. The flower we see is not seen by the infant; what the infant sees is what he has learned to see; slowly the blur of feeling differentiates, and the stem, leaves, petals, &c., once observed, are ever after observable; they then exist for the observer. Did they not exist before? Certainly they did, but only for some observant mind, not for the infant. To the mind of a philosopher, every fact of colour is a complex of visible and invisible facts, which differs from what it is in the mind of a child or a peasant as the idea of a lily in the mind of a botanist differs from that in the mind of a savage."-G. H. Lewes.