which are more excitable, follow them so close as to stand at the degree 3. These mental states, however, are still so faint, that no consciousness of them en

sues.

2d Stage of Excitement.

In the second stage, sensations and ideas, from their different excitabilities, each appear at the same degree of vividness. If they had proportionally differed in vividness, a mental consciousness of such states would have ensued. But, as I have remarked on a former occasion, (in part 4,) " when it is considered that the human mind can form no notion of the present and of the past, but from the comparative degree of vividness which, during our waking hours, subsists between sensations and ideas, and that the notion of present and past time enters into our definition of consciousness, it must follow, that when sensations arrive at the same degree of vividness as ideas, a state of mental unconsciousness must necessarily be the result."

Examples of this condition of our feelings are afforded in those moments which immediately precede our recovery from sound sleep.

3d Stage of Excitement.

In a third stage of excitement, sensations attain the 7th and ideas the 6th degree of vividness, the former becoming more vivid than the latter. The consciousness of the mind is now entire.

An important law of the mind is now called forth,

which may be thus briefly explained :-When mental feelings of any description attain a certain degree of vividness, muscular motions obey the impulse of the will.* For, in the faint feelings of our common dreams, there is a decided volition, but no contractions of the muscles follow. The particular degree necessary for muscular motions is represented in the scale as the sixth. The effect induced is, however, but feeble :

"The slumb'ring god, amazed at this new din,
Thrice strove to rise, and thrice sunk down again :
Listless he stretch'd, and gaping rubb'd his eyes,
Then falter'd thus betwixt half words and sighs.”

Another character may yet be mentioned, which distinguishes this stage of excitement. The vividness of ideas approaches so nearly to that of sensations, that recollected images of thought are often confounded with actual impressions. While, therefore, the various forms of fancy and of memory mingle together in confusion, a lethargic faintness increases the indistinctness, by imparting to the whole a dull and feeble gloom :

"The landskip such, inspiring perfect ease,
Where Indolence (for so the wizard hight)
Close-hid his castle 'mid imbowering trees,

That half shut out the beams of Phoebus bright,
And made a kind of checker'd day and night."+

* Regarding this curious law I could say much, but am prevented by the limited nature of the present work.

+ Thomson's Castle of Indolence.

4th Stage of Excitement.

In a fourth stage of excitement, sensations attain the 9th and ideas the 7th degree of vividness, the former now being more vivid than the latter.

This stage of excitement is particularly favourable for the operations of the reasoning powers. Actual impressions possess such a superior degree of vividness, that they are not easily confounded with the recollected images of thought. The attainment of a state of mind such as this, free from depressing or exciting passions, has been recommended by all moralists as indispensable for the discovery of truth. Thus the Roman writer Boethius :

"Tu quoque si vis

Lumine claro

Cernere verum

Tramite recto
Carpere callem

Gaudia pelle,
Pelle Timorem,
Nec dolor adsit,
Spemque fugato.
Nubila mens est,
Vinctaque frenis

Hæc ubi regnant."

SECTION II.

TRANSITION (marked the 4th in the Table)

From the common State of Watchfulness to perfect Sleep.

A second transition is from the ordinary state of ou waking hours to perfect sleep.

It is unnecessary to dwell upon the phenomena of this depression of our mental feelings, which are the exact reverse of the stages of excitement just described. It is sufficient to state, that sensations, from being more vivid than ideas, become more faint.

A suitable opportunity occurs, however, for noticing such mental depressions of feelings as are referable to morbific causes. These, in fact, are to be traced in all the stages of reduced vividness incidental to a transition from the state of watchfulness to that of perfect sleep. But this view, which I have taken of the effects of depressing causes, will be rendered more explicit by the following table.

TABULAR VIEW.

States of the mind occurring from depressing causes of a morbific nature.

*When sensations and ideas are equally vivid, there is no consciousness of

them.

1st, or Lethargic State.

The first state, arising from morbific causes of depression, is that which I have named the lethargic. It frequently results from paralytic affections of the nervous system, and is sometimes the consequence of intense thinking. After an undue mental excitement has been caused by the ardent study of the abstract sciences, the drowsy god then displays his benumbing influence:

"No passions interrupt his easy reign;
No problems puzzle his lethargic brain :
But dull Oblivion guards his peaceful bed,
And lazy fogs bedew his gracious head."*

But this tendency of intense study to produce stupor has been by no one better illustrated, than by Dr Crichton, in his valuable work on mental derangement. With one example, therefore, which he gives, I shall conclude my notice of the lethargic state induced by depressing causes.

"A young Swiss gentleman, for six months, had given himself up wholly to the intense study of metaphysics. An inertness of mind followed, which at last ended in a complete stupor. Without being blind,' it is said, he appeared not to see; without being deaf, he seemed not to hear; without being dumb, he did not speak. In other respects, he slept, drank, ate without relish and without aversion, without asking to eat, or without refusing to do so. This

Garth's Dispensary.