Self-remembering is the key to self-study and the ideal method to study consciousness within oneself.  Ouspensky states that, when Gurdjieff introduced him to the fourth way teaching, he immediately recognized that this practice is of profound importance.  Thus, he argues that:

"... psychology begins at this point. ... man does not remember himself but could remember himself if he made sufficient efforts. Without self-remembering there can be no study, no psychology. But if a man realizes and bears in mind that he does not remember himself, and that nobody remembers, and yet there is a possibility of self-remembering, then study begins." (1950, p. 120)

“... you can know consciousness only in yourself. Observe that I say you can know, for you can know it only when you have it. And when you have not got it, you can know that you have not got it, not at that very moment, but afterwards. I mean that when it comes again you can see that it has been absent a long time, and you can find or remember the moment when it disappeared and when it reappeared. ... by observing in yourself the appearance and the disappearance of consciousness you will inevitably see one fact which you neither see nor acknowledge now, and that is that moments of consciousness are very short and are separated by long intervals of completely unconscious, mechanical working of the machine. You will then see that you can think, feel, act, speak, work, without being conscious of it. And if you learn to see in yourselves the moments of consciousness and the long periods of mechanicalness, you will as infallibly see in other people when they are conscious of what they are doing and when they are not.
“Your principal mistake consists in thinking that you always have consciousness, and in general, either that consciousness is always present or that it is never present. In reality consciousness is a property which is continually changing. Now it is present, now it is not present. And there are different degrees and different levels of consciousness. Both consciousness and the different degrees of consciousness must be understood in oneself by sensation, by taste.” (1949, pp. 116-117)

    Despite the importance of self-remembering, defining it is a tricky business.  There are many angles from which this practice can be approached and definitions are useful–although only to a point.  One must practice self-remembering, learning to define it, as G. says, “by sensation, by taste,” in order to gain a true sense of its profound significance.  Nevertheless, Ouspensky defines self-remembering quite simply and distinguishes it from the related practice of self-observation:
 

"Self-remembering is an attempt to be aware of yourself. Self-observation is always directed at some definite function: either you observe your thoughts, or movements, or emotions, or sensations. It must have a definite object which you observe in yourself. Self-remembering does not divide you, you must remember the whole, it is simply the feeling of ‘I,’ of your own person." (1957, p. 107)

Self-observation is directed towards particular contents of experience and the activities of the centers.  In contrast, self-remembering is experiencing or feeling/sensing the whole of self.   Remembering self means being more fully present as a three-centered being, in such a way that one’s experience consists of a deeper sense and feeling that “I am here.”
    On one occasion, Gurdjieff asked a group of his pupils, “What is the most important thing that we notice during self observation?”  Dissatisfied with their answers, Gurdjieff explained that:
 

“Not one of you has noticed the most important thing that I have pointed out to you .... That is to say, not one of you has noticed that you do not remember yourselves. ... You do not feel yourselves; you are not conscious of yourselves. With you, ‘it observes’ just as ‘it speaks,’‘it thinks,’ ‘it laughs.’ You do not feel: I observe, I notice, I see. Everything still ‘is noticed,’ ‘is seen.’ ... In order really to observe oneself one must first of all remember oneself. ... Try to remember yourselves when you observe yourselves and later on tell me the results. Only those results will have any value that are accompanied by self-remembering. Otherwise you yourselves do not exist in your observations. In which case what are all your observations worth?” (1949, pp, 117-8)

At moments of self-observation, we need to remember ourselves and experience being fully present.  In this case, there is an enhanced experience of I, in addition to the observation of the psychic functions.  Ouspensky ascribes major importance to this deceptively simple idea:

"So, at the same time as self-observing, we try to be aware of ourselves by holding the sensation of ‘I am here’–nothing more, And this is the fact that all Western psychology, without the smallest exception, has missed. Although many people came very near to it, they did not recognize the importance of this fact and did not realize that the state of man as he is can be changed-that man can remember himself, if he tries for a long time."  (1957, p. 5)

    Again, it is impossible to appreciate the significance of this apparently simple practice of self-remembering until one undertakes the study of oneself on that basis.  Only then can one begin to understand Ouspensky’s claim that the study of psychology has to begin with attempts to remember oneself.    Modern psychology has erred in failing to understand the normal waking sleep state. Humans do not remember themselves and are not properly conscious, and have no “conscious self” as such.  However, they can study self in the inner world and make intentional efforts to enhance consciousness.

    Gurdjieff and Ouspensky refer to the ordinary waking state, the state of forgetfulness, as a state of “relative consciousness” or  “waking sleep.”  Self-observation and self-remembering serve in the development of self-consciousness (and objective consciousness).  Ouspensky explains some of the difficulties in understanding consciousness, particularly self-consciousness:

"The third state of consciousness is very strange. If people explain to us what the third state of consciousness is, we begin to think that we have it. The third state can be called self consciousness, and most people, if asked, say, 'Certainly we are conscious!' A sufficient time or repeated and frequent efforts of self observation is necessary before we really recognize the fact that we are not conscious; that we are conscious only potentially.  If we are asked, we say, ‘Yes, I am’, and for that moment we are, but the next moment we cease to remember and are not conscious. So in the process of self-observation we realize that we are not in the third state of consciousness, that we live only in two. We live either in sleep or in a waking sleep which, in the system, is called relative consciousness. The fourth state, which is called objective consciousness, is inaccessible to us because it can only be reached through self-consciousness, that is, by becoming aware of oneself first, so that much later we may manage to reach the objective state of consciousness." (1957, pp.4-5)

Over a period of time, the effects of self-study and self-remembering remove various obstacles to consciousness and allow the emergence of self-consciousness.  The basic framework is quite coherent and logical, although it is difficult to realize what lies behind all of these fine words.

    To realize what self-remembering is, and is not, is a long and subtle process, and various problems arise as people attempt to study and remember themselves.  Each person will tend to interpret the term according to their own associations and beliefs.   For the time being, it is most useful simply to approach the elusive practice of “self-remembering” by attempting to do it, anywhere and anytime.

    Misunderstandings and misconceptions about self-remembering  generate  errors and illusions regarding its practice.  First and foremost, people are apt to confuse being conscious of self or remembering self with thinking about ourselves, or thinking about self-remembering.  Nothing could be further from the truth.  In fact, the continual turning of the mind, as it is referred to in eastern esoteric teachings, is a major obstacle to self-remembering.  The associative thinking happens mechanically and is not something that “I” do, or could even not do.  Associative thinking and emotional concerns continually engage the attention, and prevent people from experiencing the deeper coherence, feeling and sensation that “I am here.”

“... a man must die, that is, he must free himself from a thousand petty attachments and identifications which hold him in the position in which he is. He is attached to everything in his life, attached to his imagination, attached to his stupidity, attached even to his suffering, possibly to his sufferings more than to anything else. He must free himself from this attachment. Attachment to things, identification with things, keep alive a thousand useless I’s in a man. These I’s must die in order that the big I may be born." (1949, p. 218)

"When we try to keep all these things in mind and to observe ourselves, we come to the very definite conclusion that in the state of consciousness in which we are, with all this identification, considering, negative emotions and absence of self-remembering, we are really asleep. We only imagine that we are awake. So when we try to remember ourselves it means only one thing–we try to awake. And we do awake for a second but then we fall asleep again. This is our state of being, so actually we are asleep.  We can awake only if we correct many things in the machine and if we work very persistently on this idea of awaking, and for a long time." (p. 13)

"G.'s favorite statement was that, if a man in prison was at any time to have a chance of escape, then he must first of all realize that he is in prison. So long as he fails to realize this, so long as he thinks he is free, he has no chance whatever." (1949, p. 30)