certain than that every elementary part of duration must have duration, as every elementary part of extension must have extension.

Now it must be observed, that in these elements of duration, or single intervals of successive ideas, there is no succession of ideas, yet we must conceive them to have duration; whence we may conclude with certainty, that there is a conception of duration, where there is no succession of ideas in the mind.

We may measure duration by the succession of thoughts in the mind, as we measure length by inches or feet; but the notion or idea of duration must be antecedent to the mensuration of it, as the notion of length is antecedent to its being measured.

Mr. Locke draws some conclusions from his account of the idea of duration, which may serve as a touchstone to discover how far it is genuine. One is, that if it were possible for a man awake, to keep only one idea in his mind without variation, or the succession of others, he would have no perception of duration at all; and the moment he began to have this idea, would seem to have no distance from the moment he ceased to have it.

Now that one idea should seem to have no duration, and that a multiplication of that no duration should seem to have duration, appears to me as impossible as that the multiplication of nothing should produce something.

Another conclusion which the author draws from this theory is, that the same period of duration appears long to us, when the succession of ideas in our mind is quick, and short when the succession is slow.

There can be no doubt but the same length of duration appears in some circumstances much longer than in others; the time appears long when a man is impatient under any pain or distress, or when he is eager in the expectation of some happiness: on the other hand, when he is pleased and happy in agreeable conversation, or delighted with a variety of agreeable objects that strike his senses, or his imagination, time flies away, and appears short.

According to Mr. Locke's theory, in the first of these cases the succession of ideas is very quick, and in the last very slow: I am rather inclined to think that the very contrary is the truth. When a man is racked with pain or with expectation, he can hardly think of any thing but his distress; and the more his mind is occupied by that sole object, the longer the time appears. On the other hand, when he is entertained with cheerful music, with lively conversation, and brisk sallies of wit, there seems to be the quickest succession of ideas, but the time appears shortest.

I have heard a military officer, a man of candour and observation, say that the time he was engaged in hot action always appeared to him much shorter than it really was. Yet I think it cannot be supposed, that the

succession of ideas was then slower than usual.

If the idea of duration were got merely by the succession of ideas in our minds, that succession must to ourselves appear equally quick at all times, because the only measure of duration is the number of succeeding ideas; but I believe every man capable of reflection will be sensible, that at one time his thoughts come slowly and heavily, and at another time have a much quicker and livelier motion.

I know of no ideas or notions that have a better claim to be accounted simple and original than those of space and time. It is essential both to space and time to be made up of parts, but every part is similar to the whole, and of the same nature. Different parts of space, as it has three dimensions, may differ both in figure and in magnitude; but time having

only one dimension, its parts can differ only in magnitude; and, as it is one of the simplest objects of thought, the conception of it must be purely the effect of our constitution, and given us by some original power of the mind.

The sense of seeing, by itself, gives us the conception and belief of only two dimensions of extension, but the sense of touch discovers three and reason, from the contemplation of finite extended things, leads us necessarily to the belief of an immensity that contains them. In like manner, memory gives us the conception and belief of finite intervals of duration. From the contemplation of these, reason leads us necessarily to the belief of an eternity, which comprehends all things that have a beginning and end. Our conceptions, both of space and time, are probably partial and inadequate, and therefore we are apt to lose ourselves, and to be embarrassed in our reasonings about them.

Our understanding is no less puzzled when we consider the minutest parts of time and space than when we consider the whole. We are forced to acknowledge, that in their nature they are divisible without end or limit; but there are limits beyond which our faculties can divide neither the one nor the other.

It may be determined by experiment, what is the least angle under which an object may be discerned by the eye, and what is the least interval of duration that may be discerned by the ear. I believe these may be different in different persons: but surely there is a limit which no man can exceed and what our faculties can no longer divide is still divisible in itself, and, by beings of superior perfection, may be divided into thousands of parts.

I have reason to believe, that a good eye in the prime of life may see an object under an angle not exceeding half a minute of a degree, and I believe there are some human eyes still more perfect. But even this degree of perfection will appear great, if we consider how small a part of the retina of the eye it must be, which subtends an angle of half a minute.

Supposing the distance between the centre of the eye and the retina to be six or seven tenths of an inch, the subtense of an angle of half a minute to that radius, or the breadth of the image of an object seen under that angle, will not be above the ten thousandth part of an inch. This shows such a wonderful degree of accuracy in the refracting power of a good eye, that a pencil of rays coming from one point of the object shall meet in one point of the retina, so as not to deviate from that point the ten thousandth part of an inch. It shows, likewise, that such a motion of an object as makes its image on the retina to move the ten thousandth part of an inch, is discernible by the mind.

In order to judge to what degree of accuracy we can measure short intervals of time, it may be observed, that one who has given attention to the motion of a second pendulum, will be able to beat seconds for a minute with a very small error. When he continues this exercise long, as for five or ten minutes, he is apt to err, more even than in proportion to the time, for this reason, as I apprehend, that it is difficult to attend long to the moments as they pass, without wandering after some other object of thought.

I have found by some experiments, that a man may beat seconds for one minute, without erring above one second in the whole sixty; and I doubt not but by long practice he might do it still more accurately. From this I think it follows, that the sixtieth part of a second of time is discernible by the human mind.

CHAPTER VI.

OF MR. LOCKE'S ACCOUNT OF OUR PERSONAL IDENTITY.

IN a long chapter upon identity and diversity, Mr. Locke has made many ingenious and just observations, and some which I think cannot be defended I shall only take notice of the account he gives of our own personal identity. His doctrine upon this subject has been censured by Bishop Butler, in a short essay subjoined to his Analogy, with whose sentiments I perfectly agree.

Identity, as was observed, Chap. IV. of this Essay, supposes the continued existence of the being of which it is affirmed, and therefore can be applied only to things which have a continued existence. While any being continues to exist, it is the same being; but two beings which have a different beginning or a different ending of their existence, cannot possibly be the same. To this I think Mr. Locke agrees.

He observes very justly, that to know what is meant by the same person, we must consider what the word person stands for; and he defines a person to be an intelligent being, endowed with reason and with consciousness, which last he thinks inseparable from thought.

From this definition of a person, it must necessarily follow, that while the intelligent being continues to exist and to be intelligent, it must be the same person. To say that the intelligent being is the person, and yet that the person ceases to exist, while the intelligent being continues, or that the person continues while the intelligent being ceases to exist, is to my apprehension a manifest contradiction.

One would think that the definition of a person should perfectly ascertain the nature of personal identity, or wherein it consists, though it might still be a question how we come to know and be assured of our personal identity.

Mr. Locke tells us, however, "that personal identity, that is, the sameness of a rational being, consists in consciousness alone, and, as far as this consciousness can be extended backwards to any past action or thought, so far reaches the identity of that person. So that whatever hath the consciousness of present and past actions, is the same person to whom they belong."

This doctrine has some strange consequences, which the author was aware of. Such as, that if the same consciousness can be transferred from one intelligent being to another, which he thinks we cannot show to be impossible, then two or twenty intelligent beings may be the same person. And if the intelligent being may lose the consciousness of the actions done by him, which surely is possible, then he is not the person that did those actions; so that one intelligent being may be two or twenty different persons, if he shall so often lose the consciousness of his former actions.

There is another consequence of this doctrine, which follows no less necessarily, though Mr. Locke probably did not see it. It is, that a man may be, and at the same time not be, the person that did a particular

action.

Suppose a brave officer to have been flogged when a boy at school, for robbing an orchard, to have taken a standard from the enemy in his first campaign, and to have been made a general in advanced life: suppose also, which must be admitted to be possible, that when he took the standard,

he was conscious of his having been flogged at school, and that when made a general he was conscious of his taking the standard, but had absolutely lost the consciousness of his flogging.

These things being supposed, it follows, from Mr. Locke's doctrine, that he who was flogged at school is the same person who took the standard, and that he who took the standard is the same person who was made a general. Whence it follows, if there be any truth in logic, that the general is the same person with him who was flogged at school. But the general's consciousness does not reach so far back as his flogging: therefore, according to Mr. Locke's doctrine, he is not the person who was flogged. Therefore the general is, and at the same time is not, the same person with him who was flogged at school.

Leaving the consequences of this doctrine to those who have leisure to trace them, we may observe, with regard to the doctrine itself,

First, That Mr. Locke attributes to consciousness the conviction we have of our past actions, as if a man may now be conscious of what he did twenty years ago. It is impossible to understand the meaning of this, unless by consciousness be meant memory, the only faculty by which we have an immediate knowledge of our past actions.

Sometimes, in popular discourse, a man says he is conscious that he did such a thing, meaning that he distinctly remembers that he did it. It is unnecessary, in common discourse, to fix accurately the limits between consciousness and memory. This was formerly shown to be the case with regard to sense and memory: and therefore distinct remembrance is sometimes called sense, sometimes consciousness, without any inconvenience.

But this ought to be avoided in philosophy, otherwise we confound the different powers of the mind, and ascribe to one what really belongs to another. If a man can be conscious of what he did twenty years or twenty minutes ago, there is no use for memory, nor ought we to allow that there is any such faculty. The faculties of consciousness and memory are chiefly distinguished by this, that the first is an immediate knowledge of the present, the second an immediate knowledge of the past.

When, therefore, Mr. Locke's notion of personal identity is properly expressed, it is, that personal identity consists in distinct remembrance': for, even in the popular sense, to say that I am conscious of a past action, means nothing else than that I distinctly remember that I did it.

Secondly, It may be observed, that in this doctrine, not only is consciousness confounded with memory, but, which is still more strange, personal identity is confounded with the evidence which we have of our personal identity.

It is very true, that my remembrance that I did such a thing is the evidence I have that I am the identical person who did it. And this, I am apt to think, Mr. Locke meant: but to say that my remembrance that I did such a thing, or my consciousness, makes me the person who did it, is, in my apprehension, an absurdity too gross to be entertained by any man who attends to the meaning of it: for it is to attribute to memory or consciousness a strange magical power of producing its object, though that object must have existed before the memory or consciousness which produced it.

Consciousness is the testimony of one faculty; memory is the testimony of another faculty and to say that the testimony is the cause of the thing testified, this surely is absurd, if any thing be, and could not have been said by Mr. Locke, if he had not confounded the testimony with the thing stified.

When a horse that was stolen is found and claimed by the owner, the only evidence he can have, or that a judge or witnesses can have, that this is the very identical horse which was his property, is similitude. But would it not be ridiculous from this to infer that the identity of a horse consists in similitude only? The only evidence I have that I am the identical person who did such actions is, that I remember distinctly I did them; or, as Mr. Locke expresses it, I am conscious I did them. To infer from this, that personal identity consists in consciousness, is an argument, which, if it had any force, would prove the identity of a stolen horse to consist solely in similitude.

Thirdly, Is it not strange that the sameness or identity of a person should consist in a thing which is continually changing, and is not any two minutes the same?

Our consciousness, our memory, and every operation of the mind, are still flowing like the water of a river, or like time itself. The consciousness I have this moment, can no more be the same consciousness I had last moment than this moment can be the last moment. Identity can only be affirmed of things which have a continued existence. Consciousness, and every kind of thought, is transient and momentary, and has no continued existence; and therefore, if personal identity consisted in consciousness, it would certainly follow, that no man is the same person any two moments of his life; and as the right and justice of reward and punishment is founded on personal identity, no man could be responsible for his actions.

But though I take this to be the unavoidable consequence of Mr. Locke's doctrine concerning personal identity, and though some persons may have liked the doctrine the better on this account, I am far from imputing any thing of this kind to Mr. Locke. He was too good a man not to have rejected with abhorrence, a doctrine which he believed to draw this consequence after it.

Fourthly, There are many expressions used by Mr. Locke in speaking of personal identity, which to me are altogether unintelligible, unless we suppose that he confounded that sameness or identity, which we ascribe to an individual, with the identity which in common discourse is often ascribed to many individuals of the same species.

When we say that pain and pleasure, consciousness and memory, are the same in all men, this sameness can only mean similarity or sameness of kind; but that the pain of one man can be the same individual pain with that of another man, is no less impossible than that one man should be another man: the pain felt by me yesterday, can no more be the pain I feel to-day, than yesterday can be this day; and the same thing may be said of every passion and of every operation of the mind: the same kind or species of operation may be in different men, or in the same man at different times; but it is impossible that the same individual operation should be in different men, or in the same man at different times.

When Mr. Locke therefore speaks of "the same consciousness being continued through a succession of different substances;" when he speaks of "repeating the idea of a past action, with the same consciousness we had of it at the first," and of "the same consciousness extending to actions past and to come;" these expressions are to me unintelligible, unless he means not the same individual consciousness, but a consciousness that is similar or of the same kind.

If our personal identity consists in consciousness, as this consciousness cannot be the same individually any two moments, but only of the same