agreeable sensations, and be afraid of the return of those which were painful. If the sensations of smell and sound are both excited in his mind at the same time, he can attend to either of them he chooses, and withdraw his attention from the other, or he can withdraw his attention from both, and fix it on some sensation he has felt formerly. In this manner, he might be led, merely by sensations existing in his mind, and conveying to him no imformation concerning matter, to exercise many of his most important faculties; and amidst all these different modifications and operations of his mind, he would feel, with irresistible conviction, that they all belong to one and the same sentient and intelligent being; or, in other words, that they are all modifications and operations of himself. I say nothing, at present, of the various simple notions, (or simple ideas, as they are commonly 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.

The remarks which I have offered on this doctrine will not appear superfluous to those who recollect that, although it has, for many years past, been a subject of controversy in England, it continues still to be implicit

ly adopted by the best philosophical writers in France; and that it has been employed by some of them to support the system of materialism, and by others to show, that the intellectual distinctions between man and brutes arise entirely from the differences in their animal organization, and in their powers of external perception.

CHAPTER SECOND.

OF ATTENTION.

WHEN 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.

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 judgment is found

ed 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 farther 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 it; and that it requires a considerable degree of reflection, to enable the 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: 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 con

"It

nexion 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 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 connexion 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." The same observation has been made by Locke,* and by most of the writers on the subject of education.

But although the connexion 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

ch. x.

Memory depends much on attention and repetition." Locke's Essay, b. i.

Some important observations on the subject of attention occur in different parts of Dr. Reid's writings, particulady in his Essays on the Intellectual Powers of Man, p. 62; and in his Essays on the Active Powers of Man, p. 78, et seq.-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. I shall have occasion, in another part of this work, to treat of habits of inattention in general, and to suggest some practical hints with respect to the culture both of the powers of observation and reflection. The view