monly called,) which would arise in his mind; for example, the ideas of number, of duration, of cause and effect, of personal identity; all of which, though perfectly unlike his sensations, could not fail to be suggested by means of them. Such a being, then, might know all that we know of mind at present; and as his language would be appropriated to mind solely, and not borrowed by analogy from material phenomena, he would even possess important advantages over us in conducting the study of pneumatology.

From these observations it sufficiently appears, what is the real amount of the celebrated doctrine, which refers the origin of all our knowledge to our sensations; and that, even granting it to be true, (which, for my own part, I am disposed to do, in the sense in which I have now explained it,) it would by no means follow from it, that our notions of the operations of mind, nor even many of those notions which are commonly suggested to us, in the first instance, by the perception of external objects, are necessarily subsequent to our knowledge of the qualities, or even of the existence, of matter.

CHAPTER II.

OF ATTENTION.

When

Attention necessary to memory, if not to perception. we are deeply engaged in conversation, or occupied with any speculation that is interesting to the mind, the surrounding objects either do not produce in us the perceptions they are fitted to excite; or these perceptions are instantly forgotten. A clock, for example, may strike in the same room with us, without our being able, next moment, to recollect whether we heard it or not.

In these, and similar cases, I believe, it is commonly taken

for granted, that we really do not perceive the external object. From some analogous facts, however, I am inclined to suspect that this opinion is not well founded. A person who falls asleep at church, and is suddenly awaked, is unable to recollect the last words spoken by the preacher; or even to recollect that he was speaking at all. And yet, that sleep does not suspend entirely the powers of perception may be inferred from this, that if the preacher were to make a sudden pause in his discourse, every person in the congregation who was asleep would instantly awake. In this case, therefore, it appears, that a person may be conscious of a perception, without being able afterwards to recollect it.

Other instances illustrating this fact. - Many other instances of the same general fact might be produced. When we read a book, (especially in a language which is not perfectly familiar to us,) we must perceive successively every different letter, and must afterwards combine these letters into syllables and words, before we comprehend the meaning of a sentence. This process, however, passes through the mind, without leaving any trace in the memory.

It has been proved by optical writers, that, in perceiving the distances of visible objects from the eye, there is a judgment of the understanding antecedent to the perception.* In some cases, this

* ["It is, I think, agreed by all," says Berkeley, "that distance of itself, and immediately, cannot be seen. For distance being a line directed endwise to the eye, it projects only one point in the fund of the eye; which point remains invariably the same, whether the distance be longer or shorter." Take the following example. If a traveller on a dark night and a strange road secs before him a fixed light which is a mere bright point, he cannot tell whether it is a rod or a mile distant from him; he may even confound it with a star near the horizon. If the light, however, has a visible magnitude, and especially if he can see it flicker, so that he can form some guess as to its origin and nature, he may estimate its distance very correctly. But even in this case, he does not see its distance, but infers it from the magnitude, color, flickering, or some other circumstance which previous experience has taught him the meaning of.

Many other facts show the necessity of experience before we can obtain correct notions of distance from the eye alone. We are not so much accus

judgment is founded on a variety of circumstances combined together; the conformation of the organ necessary for distinct vision; the inclination of the optic axes; the distinctness or indistinctness of the minute parts of the object; the distances of the intervening objects from each other, and from the eye; and, perhaps, on other circumstances besides these: and yet, in consequence of our familiarity with such processes from our earliest infancy, the perception seems to be instantaneous; and it requires much reasoning, to convince persons unaccustomed to philosophical speculations, that the fact is otherwise.

Another instance, of a still more familiar nature, may be of use, for the further illustration of the same subject. It is well known that our thoughts do not succeed each other at random, but according to certain laws of association, which modern philosophers have been at much pains to investigate. It frequently, however, happens, particularly when the mind is animated by conversation, that it makes a sudden transition from one subject to another, which, at first view, appears to be very remote from and that it requires a considerable degree of reflection, to enable a person himself by whom the transition was made, to ascertain what were the intermediate ideas. A curious instance of such a sudden transition is mentioned by Hobbes in his Leviathan. "In a company," (says he,) "in which the conversation turned on the civil war, what could be conceived more impertinent, than for a person to ask abruptly, What was the value of a Roman denarius? On a little reflection, however, I was easily able to trace the train of thought which suggested the question:

it;

tomed to see objects at a distance from us in a vertical line, as in a horizontal one; hence, the same visible appearance, if placed directly above or below our own position, does not suggest the same magnitude, as when seen at an equal distance on a level with the eye. If we are standing on the seashore, a ship distant a few hundred feet appears of the natural size, and men, not pigmies, walk her deck. But ascend to the brow of the cliff, and

"The fishermen, that walk upon the beach,
Appear like mice; and yon tall anchoring bark
Diminished to her cock; her cock, a buoy
Almost too small for sight."]

for the original subject of discourse naturally introduced the history of the king, and of the treachery of those who surrendered his person to his enemies; this again introduced the treachery of Judas Iscariot, and the sum of money which he received for his reward. And all this train of ideas," says Hobbes, "passed through the mind of the speaker in a twinkling, in consequence of the velocity of thought." It is by no means improbable, that if the speaker himself had been interrogated about the connection of ideas, which led him aside from the original topic of discourse, he would have found himself, at first, at a loss for an

answer.

In the instances which have been last mentioned, we have also a proof, that a perception or an idea, which passes through the mind without leaving any trace in the memory, may yet serve to introduce other ideas connected with it by the laws of association. Other proofs of this important fact shall be mentioned afterwards.

When a perception or an idea passes through the mind, without our being able to recollect it the next moment, the vulgar themselves ascribe.our want of memory to a want of attention. Thus, in the instance already mentioned, of the clock, a person, upon observing that the minute-hand had just passed twelve, would naturally say, that he did not attend to the clock when it was striking. There seems, therefore, to be a certain effort of mind upon which, even in the judgment of the vulgar, memory in some measure depends; and which they distinguish by the name of attention.

The connection between attention and memory has been remarked by many authors. "Nec dubium est," (says Quinctilian, speaking of memory,) "quin plurimum in hac parte valeat mentis intentio, et velut acies luminum a prospectu rerum quas intuetur non aversa." ["There is no doubt that great effect is produced by close attention, just as vision is most perfect when the eyes are steadily fixed on the object seen."] The same observation has been made by Locke, and by most of the writers on the subject of education.

Attention a separate faculty of the mind. But although the

*

connection between attention and memory has been frequently remarked in general terms, I do not recollect that the power of attention has been mentioned by any of the writers on pneumatology, in their enumeration of the faculties of the mind; nor has it been considered by any one, so far as I know, as of sufficient importance to deserve a particular examination. Helvetius, indeed, in his very ingenious work, De l'Esprit, has entitled one of his chapters, De l'inégale capacité d'Attention; but what he considers under this article, is chiefly that capacity of patient inquiry, (or as he calls it, continuous attention,) upon which philosophical genius seems in a great measure to depend. He has also remarked, with the writers already mentioned, that the impression which any thing makes on the memory, depends much on the degree of attention we give to it; but he has taken no notice of that effort which is absolutely essential to the lowest degree of memory. It is this effort that I propose to consider at present: not those different degrees of attention which imprint things more or less deeply on the mind, but that act or effort without which we have no recollection or memory whatever. Some attention necessary for any act of memory whatever. — With respect to the nature of this effort, it is perhaps impossible for us to obtain much satisfaction. We often speak of greater and less degrees of attention; and, I believe, in these cases, conceive the mind (if I may use the expression) to exert itself with different degrees of energy. I am doubtful, however, if this expression conveys any distinct meaning. For my own part, I am inclined to suppose, (though I would by no means be understood to speak with confidence,) that it is essential to memory, that the perception or the idea that we would wish to ren ber, should remain in the mind for a certain space of time, and should

* Some important observations on the subject of attention occur in different parts of Dr. Reid's writings. To this ingenious author we are indebted for the remark, that attention to things external is properly called observation; and attention to the subjects of our consciousness, reflection. He has also explained the causes of the peculiar difficulties which accompany this last exertion of the mind, and which form the chief obstacles to the progress of pneumatology.