There can be little doubt, but that the circumstance of our muscular feelings of resistance being less liable to delusion than those of sight, has given rise to a variety of notions which, from a very early period, have been entertained on the nature of spiritual beings. Thus, Lucretius, as he is translated by Creech:

"Nor must we think these are the blest abodes,
The quiet mansions of the happy gods,

Their substance is so thin, so much refin'd,

Unknown to sense, nay, scarce perceiv'd by mind;
Now, since these substances can't be touch'd by man,
They cannot touch those other things that can ;
For whatsoe'er is touch'd, that must be touch'd again.
Therefore, the mansions of those happy pow'rs
Must be all far unlike, distinct from ours;

Of subtle natures suitable to their own;"

(and, as the translator quaintly adds,)

"All which, by long discourse, I'll prove anon."

Lastly, I might observe, that the olfactory organs may occasionally be the medium through which ideas. of smell are so intensely excited, as to give rise to mental illusions. Burton, on the authority of Petrus Forestus, relates, that "a minister, through precise fasting in Lent, and over much meditation, became desperate, thought he saw divells in his chamber, and that he could not be saved. He smelled nothing, as he said, but fire and brimstone, and was already in hell, and would aske them still if they did not smell as much. I told him he was melancholy, but he laughed me to scorne, and replied that hee saw divells, talked with them in good earnest, and would spit in my face, and aske me if I did not smell brimstone."

R

CHAPTER III.

THE VARIOUS DEGREES OF EXCITEMENT, OF WHICH IDEAS, OR THE RENOVATED FEELINGS OF THE MIND, ARE SUSCEPTIBLE.

"Men must acquire a very peculiar and strong habit of turning their eye inwards, in order to explore the interior regions and recesses of the MIND-the hollow caverns of deep thoughtthe private seats of fancy-and the wastes and wildernesses, as well as the more fruitful and cultivated tracts of this obscure climate."

We are now literally entering on the investigation of what the French metaphysicians name ideology, a subject which, from the manner it has been treated, has recently incurred a censure that it too well deserves. Ideology is, no doubt, a part of human physiology; but it has far outgrown its parent science in point of extent, and is still far inferior to it in the means of verification. Let the metaphysician always avail himself of the experiments of physiology as far as he is able; but let not the physiologist imagine that he can ever derive a reciprocal assistance from metaphysics. It is possible, however, to transfer credulity from one extreme to the other;-to yield a faith as implicit to the probabilities of the scientific

physiologist, as is usually required for the dogmas of pneumatology."*

These are, indeed, excellent remarks, from the just severity of which I can scarcely flatter myself with the prospect of an entire escape. The discussion will be, however, hazarded.

This investigation has hitherto been conducted upon the principle, that the various degrees of vividness of which our mental states are susceptible correspond to certain conditions of the sanguineous system; and that the natural source of the excitement which is imparted to the circulation, and of the corresponding vividness which the feelings of the mind receive, is attributable to the influence of the brain and nerves.

In the next place, several proofs were adduced in support of the conclusion, that organs of sensation were the common medium through which actual impressions were induced, and past feelings or ideas were renovated.

According, then, to this view, every organ of feeling, which is no less the organ of ideas than of sensations, must be considered as supplied with its own vital fluid, and as more or less influenced by nervous matter. To the various stimulated conditions, therefore, incidental to the vascularity of each organ of feeling, the vividness of sensations and ideas corresponds.

*Notes on Magendie's Physiology, by Dr Milligan. See his translation of this work, page 423.

I shall now attempt a description of the various degrees of excitement incidental to ideas, when exclusively rendered intense, premising, however, that such gradations are to be chiefly distinguished when the vision is affected.

1st Stage of Excitement.

By a principle of the mind, purely intellectual, the impressions which may at any time be induced on the seat of vision, suggest the notion of groups of sensible figures, each varying in hue and intensity, and each included in a distinct outline. While this mental operation is going on, each affected point of the retina becomes subject to a law (the consideration of which would detain us too long), whereby its vividness is considerably modified. The effect is as follows:

The nerves which impart their influence to visual sensations, first render more vivid those impressed points of the retina which give rise to the outlines of forms, and then extend their influence to the interior and central points of each figure. Thus, when we survey a landscape composed of such multifarious objects as woods, mountains, houses, or lakes, it will be found that the outlines of each of these visible forms first become distinct, or bright, and that this distinctness or vividness is in each of them gradually propagated to the interior or central parts of the figure.

In a short time, however, the outlines of each form which may have been impressed on the retina, become less clear to the vision, while the interior im

pressed points become more distinct. This fact indicates, that the vivifying influence has extended to the centre of the visual form. The process of excitement then gradually subsides. The faintness which has commenced at the outline of the figure, extends itself to the interior, so as to convey the notion of a gradual evanescence, until a more general indistinctness becomes the ultimate result.

Such is the vivifying influence imparted by the nerves to actual impressions; we may therefore advert to their apparent action, when past feelings are renovated on the surface of the retina.

Past feelings never begin to be renovated upon the surface of the retina, until the outlines of such figures as are formed by the actual impressions of luminous. bodies have become evanescent. It is therefore on such parts of the seat of vision as have ceased to be affected by particles of light, that the recollected images of the mind may be traced. Hence, when any morbific stimulus gives an undue degree of intensity to the nerves which assist in renovating past feelings, the outlines of such ideal figures as arise by the law of association appear to be formed on the fading outlines of sensible forms. "I do not remember," says a writer on phantasms produced by disease, in a paper which I have before quoted, "by what gradation it was, that the frequently changing appearances before the sight gave place to another mode of delusive perception, which lasted for several days. All the irregularly figured objects, such as the curtains or clothes, were so far transformed, that they seemed to afford outlines of figures, of faces, animals, flowers, and other