the ladders of the mind are the clues which we use to track down items of knowledge which can not be immediately remembered . the organisation and the shelves will form important topics in our later discussion . the work that goes on at the bench must also be considered . for here the items which go into the store may be taken to pieces and reassembled , and a sketch may be made of their internal construction . both the item and the sketch can then go into the store . in the mind it is the stored items which constitute our memory and it is the stored sketches which constitute our understanding . thus reading for understanding means taking items of knowledge to pieces as we read them and seeing how the pieces are connected . a book is arranged to start at the beginning of the first chapter and to finish at the end of the last chapter . this seems natural enough but in fact it is purely an arrangement to suit authors , printers and booksellers . it does not at all correspond to the needs of the reader &apos;s mind . for a piece of understood knowledge is not a mere succession of ideas . it is a pattern of connected ideas . some of the ideas in a book , though connected , may occur on pages which are widely separated . if books were designed to meet the needs of the reader they would be printed on one side of the paper only and not bound . they would be loose-leaf books . and the reader should have a large table on which he could spread out the leaves and see the connections of meaning . of course there are many practical objections to such a method of printing but we must ask how can the reader overcome the handicaps which the present design of books imposes on him ? this leads us to consider the reader &apos;s job . my main object in this book is to show the solitary student what his job is . for in order to become an effective reader you have to learn how to learn , to learn how to remember and to learn how to know . this is not a passive process but a real job of work . for the serious student it can be a very satisfying job and can take him a long way in navigating the seas of knowledge . to each of these three processes , learning , remembering , and knowing , there are four possible approaches . these are : ( 1 ) the philosopher &apos;s approach ( 2 ) the psychologist &apos;s approach ( 3 ) the teacher &apos;s approach ( 4 ) the learner &apos;s approach . the solitary learner should aim at mastering all four approaches . he must be his own philosopher , his own psychologist and his own teacher . as a philosopher he will want to know the meanings of these important words learning , remembering and knowing , or rather to decide what meanings they are to have for him . for they have many meanings . he needs to clarify them , to see their relations one to another and also to his objective . as a psychologist he needs to observe himself at work ( and others too if possible ) and to find out what sort of processes are going on when he is coming to grips with new knowledge . it is a very variable process and he needs to grasp the nature of the variables which control his efficiency as a learner . he may discover that many of his assumptions and preconceptions about the nature of learning are unsound . he must become a critic of his own methods and an experimenter in the discovery of better methods . he can not expect the professional psychologist to tell him what is best for him because every individual is different . the psychologist can tell him what the variables are but not how they combine in his particular case . as a teacher he is , of course , in an anomalous position . the ordinary teacher is teaching what he knows . the self-teacher would seem to be a contradiction . but the contradiction is more apparent than real . it rests on the mistaken notion that the teacher has something which he is passing on to the learner . this is only superficially true . the learner is not a passive recipient . he already has a certain store of knowledge and a certain vocabulary . the job of the teacher is to set the learner &apos;s vocabulary to work on the existing store so as to make it grow . he does not simply pack new things into the store . the solitary learner has to find out how to do this for himself , with the help of books . he uses his vocabulary to ask questions and uses the books to find the answers . thus learning how to learn means becoming your own philosopher , your own psychologist and your own teacher . you will then be a well-established learner and the world will be at your feet . one . the mind . although the word mind has given rise to endless controversy among philosophers and psychologists , many of whom would like to abolish it from the dictionary , most of us obstinately go on using it . it is short and familiar and its many meanings can be otherwise expressed only by cumbersome and abstract terms which then introduce new difficulties . but it is advisable , in any particular context , to narrow down its meaning so as to avoid confusion . mind has often been contrasted with matter in such a way as to suggest that the two are somehow opposed and incompatible . and then you get a knock on the head and all evidence of mind vanishes , at any rate for some time . it seems very difficult to detach the mind from the brain , and all the biological , surgical and pharmacological evidence points to a very close connection . there is a lot to be said for keeping the word soul to stand for what many believe to be the imperishable essence of a man which is supposed to persist apart from the body , and to reserve the more prosaic word mind for the basis of all those experiences and phenomena which are clearly associated with the brain . can we now put forward any reasonably clear picture of this basis of mental phenomena ? the physicists have succeeded remarkably well , with the atomic theory , in giving a clear and detailed picture of the basis of such material phenomena as chemical action , magnetism , the behaviour of gases and so on . where has psychology got to in its theories of mind ? are there any ultimate units of mind akin to the atoms of matter ? at one time it was thought that mind could indeed be analysed into discrete bits . these bits were identified as elementary sensations . these were thought to combine together to form compound experiences by analogy with the way atoms of matter combine to form molecular compounds . but this view led to too many difficulties and was finally abandoned . nevertheless the search for basic units of mind has gone on and will doubtless continue , for it is the aim of science to discover ultimate units . we must beware , however , of supposing that there must be any close analogy between the units of quite different sciences . for example the success of the atomic theory in physics might lead us to suppose that the ultimate units of geometry must be points . it would be more correct to regard operations as the ultimate units of geometry . there have been many conflicting tendencies in psychology in its search for ultimate units and here we can only indicate what seems to be the most promising concept which is current today . it is known as the schema . it is not an easy concept and if I try to make it concrete it will be at the cost of over-simplification but even so it may be better than a meaningless abstraction . the following conversation between Hamlet and Polonius shows that Shakespeare had at any rate an intuitive grasp of the notion : Hamlet : do you see yonder cloud that &apos;s almost in shape of a camel ? Polonius : by the mass , and &apos;t is like a camel , indeed . Hamlet : methinks , it is like a weasel . Polonius : it is backed like a weasel . Hamlet : or like a whale ? Polonius : very like a whale . now the whale , the camel etc , were not in the sky . the clouds are mere aggregates of water-drops . the whale , etc , were in the minds of Hamlet and Polonius . but they could both see the cloud . thus an image of the cloud was also in their minds . moreover they knew it to be a cloud . yet they could see animals in it . this is the important fact about mental phenomena . the physical cloud in the sky is just itself , made of water-drops . the mental cloud is a multiplicity . to begin with it is a pattern of brain-processes , just as physical as the water-drops . but it is experienced ( 1 ) as a cloud , ( 2 ) as a whale , ( 3 ) as a camel and so on . we can not dismiss these as illusions for it is just the occurrence of such illusions that we seek to explain - besides why is it illusory to see the thing as a whale but not illusory to see it as a cloud ? and how did Hamlet know it was really a cloud ? for the moment we need not concern ourselves with these last questions . what we have to grasp is that there are patterns of brain-activity of different kinds . there are patterns which result directly from processes such as seeing , hearing , etc , e.g that which is experienced as the shape of the cloud ( but not yet identified as such ) . and there are patterns which result in interpretations such as cloud , whale , camel , etc . the image is fairly steady and durable . the interpretations can shift very rapidly . these interpretations are called schemas ( or more pedantically schemata ) . at one time mind used to be identified with consciousness . but consciousness simply refers to the stream of changing experiences . it will simplify our explanations if we regard consciousness as a property of mind rather than as mind itself . if we define mind as the totality of schemas in a single brain and regard consciousness as a certain transitory state which any schema , or group of schemas , can assume , we can give a more consistent account of our experiences and interpretations . before going further we should try to face what is an almost inevitable difficulty for anyone approaching the study of mind for the first time . it is the tendency to get things the wrong way round . as a psychologist I am constantly encountering this tendency in friends and acquaintances . they think there is something inevitably queer about psychology and this feeling of queerness usually boils down to a quite mistaken belief that the psychologist first looks into his own mind and then interprets other people &apos;s minds by what he has found in his own . this is what I mean by getting things the wrong way round . he is far more likely to find out about how his own mind works by looking at other people &apos;s . for although looking inwards ( or introspecting as it is called ) , is not entirely ruled out , nowadays most psychologists would agree that it is one of the most unreliable methods of getting any precise information . and so they prefer objective methods . since they can not directly look into the mental processes of another person they observe his visible behaviour and then try to give theoretical interpretations of what lies behind this behaviour . this is no more queer than the method of the doctor who observes signs , and records symptoms , and diagnoses the inner states responsible for them . he may never have had the disease himself but he can nevertheless identify it . similarly the psychologist has to be prepared to observe and make inferences about all kinds of processes in other people , whether or not they correspond with anything in his own experience . we know very little about the patterns of brain-activity which provide our schemas , nor do we need to know as far as psychology is concerned - these patterns are the concern of the neuro-physiologists . 