§ 1. Presented Objects as Data.—Psychology has to discuss mental processes, such as sensation, perception, attention, volition, and the like. But except in the case of pure sensation,* none of these processes can either exist or be conceived apart from a presented object. We cannot attend, perceive, or will, without perceiving, willing, or attending to something. Now, the object which is presented to any individual subject at any moment exists for it at that moment only in virtue of subjective processes which are then occurring, or which have occurred previously. The development of an individual mind is at the same time the development of the objective world as presented to that individual mind. The limits of its possible development are also the limits of the real world as a possible presentation to its consciousness. It follows from this that presented objects are most essential and important data for psychology. Being the effects of psychological causes, they form an indispensable startingpoint in investigating the nature of these causes. In this respect psychology presents an analogy to other sciences of development, such as geology and biology. Geology finds an actual formation of the earth's crust: it finds a certain arrangement of strata, and it inquires by what processes this arrangement has arisen.

* This exception will be explained in Book ii., Ch. 1 Definition Of Sensation. Sensation and Stimulus.

Similarly, psychology finds a certain world of objects presented, let us say, to an educated Englishman of the nineteenth century, and it inquires how this world has come to be presented. The geologist finds different strata arranged according to the successive periods of their formation. Similarly, the psychologist finds different psychological strata. The world of the young child, or the world of the Australian aborigine, are comparatively primitive formations; and the psychological problem is to discover how the transition has been made from these earlier stages to the later stages with which civilised adults are now familiar. Sometimes the arrangement of geological strata is disturbed by volcanic conditions; similar upheavals also take place in the case of mind, in the various forms of insanity.

Let us take a single example of a presented object as a psychological datum. A man looks into a stereoscope, and he is asked what he sees. He replies that he sees a cathedral, looking solid in the same manner as an actual cathedral would look solid. He may go on to describe the object in detail, and he need not at any point in his description use psychological terms. He will speak, not of perceptions, feelings, and sensations, but of the spire, the roof, the windows, etc. Now spire, roof, and windows, whether of an actual church, or of one seen through a stereoscope, are not subjective processes; nevertheless, solid figure as seen through a stereoscope is a most important datum for the psychological theory of the processes by which we perceive the third dimension of space. The appearance of solidity is produced, not by a solid thing, but by two flat surfaces on which are drawn representations of the cathedral or other object as seen from different points of view; we know, therefore that the perception of a solid object depends on processes which do not involve as their necessary condition the operation on the organ of vision of that solid object itself. We find by a process of exclusion that the only essential conditions which can be operative in producing the distinctive stereoscopic effect are certain peculiar experiences connected with the use of the two eyes. These experiences are not of course part of the object; they only become known through the psychological inquiry which attempts to account for the presentation of the object. The special importance of this case arises from the presentation of the object taking place under experimental conditions which can be precisely analysed.

But the general method is by no means confined to experimental cases. "Since the whole world, as it exists for an individual consciousness, whether from a practical, theoretical, or aesthetic point of view, has come so to exist through prior mental process, it may be said that there is no objective fact which is not capable of being utilised by the psychologist. From this point of view we may say, with Dr. Ward, that 'the whole choir of heaven and furniture of earth,' so far as they are known, are data for psychology. (Article 'Psychology,' Encyclopaedia Britannica, 9th ed., vol. xx., p. 38). So too, are all works of imagination, e.g., the Iliad or Hamlet or Grimm's Fairy Tales, and all rules of conduct, e.g., Roman law, the Brahman ritual, the four books of Confucius and Mencius. We must, however, carefully note that mere examination of mental products is valueless for psychology, except in so far as it helps us to trace mental process. This purpose is best served when we can arrange the products as parts of a historical series, in which each may be treated as the goal of preceding, and the startingpoint of succeeding, development. Thus we may profitably compare the views of the world as it presented itself to Homer, to Socrates, and to Darwin respectively. Hence the great importance of philology and anthropology to the science of mind. The products of thought are embodied in language, so that the comparison of the vocabulary and of the syntactic structure of different languages is a means of comparing different stages of mental evolution. The comparative study of the religious and other beliefs of primitive races has the same kind of psychological value, and the same holds good as regards their technical and artistic productions. Again, apart from any reference to historical order, we may compare the same object as it is presented to different minds, or to the same mind under different conditions. This course yields important results, when we can assign definite circumstances on which the variation depends. Thus, by comparing space as it exists for persons possessed both of sight and touch, with space as it exists for the blind, we may obtain valuable data for determining the part played by visual experience in the development of this perception. A flood of light is thrown on the conditions of mental development in general by examination of the cases of such abnormal individuals as Laura Bridgman or Helen Keller.* Under the same head come the data supplied by mental pathology, including cases of aphasia, psychic blindness, and so forth." It should be borne in mind that a presented object as a datum of psychology need have no actual existence in the real world. The solid figure seen in the stereoscope is not actually present; hut it is none the less perceived, and that is all with which psychology has any concern. Its real presence or absence is a matter of physical fact, not of psychical fact. Its absence is important for psychology only because it involves the absence of certain conditions which might otherwise be supposed to be essential to the presentation of solidity.

* Laura Bridgman and Helen Keller were deprived almost from birth of the senses of sight and hearing; and yet both reached a high degree of mental development. For Laura Bridgman see Stanley Hall's article in Mind, O.S. iv., p. 149. For Helen Keller see Mind, O.S. xiii., p. 314, xiv., p. 305, and N.S. i., p. 574, ii., p. 280.

Analytic Psychology, vol. i., pp. 911.