It will be seen that a synaesthesia—which may involve taste, smell, and other senses besides hearing and sight—causes an impression of one sensory order to be automatically and involuntarily linked on to an impression of another totally different order. In other words, we may say that the one impression becomes the symbol of the other impression, for a symbol—which is literally a throwing together—means that two things of different orders have become so associated that one of them may be regarded as the sign and representative of the other.

There is, however, another still more natural and fundamental form of symbolism which is entirely normal, and almost, indeed, physiological. This is the tendency by which qualities of one order become symbols of qualities of a totally different order, because they instinctively seem to have a similar effect on us. In this way, things in the physical order become symbols of things in the spiritual order. This symbolism penetrates indeed the whole of language; we cannot escape from it. The sea is deep, and so also may thoughts be; ice is cold, and we say the same of some hearts; sugar is sweet, as the lover finds also the presence of the beloved; quinine is bitter, and so is remorse. Not only our adjectives, but our substantives and our verbs are equally symbolical. To the etymological eye every sentence is full of metaphor, of symbol, of images that, strictly and originally, express sensory impressions of one order, but, as we use them to-day, express impressions of a totally different order. Language is largely the utilisation of symbols. This is a well-recognised fact which it is unnecessary to elaborate.[131]

An interesting example of the natural tendency to symbolism, which may be compared to the allied tendency in dreaming, is furnished by another language, the language of music. Music is a representation of the world—the internal or the external world—which, except in so far as it may seek to reproduce the actual sounds of the world, can only be expressive by its symbolism. And the symbolism of music is so pronounced that it is even expressed in the elementary fact of musical pitch. Our minds are so constructed that the bass always seems deep to us and the treble high. We feel it incongruous to speak of a high bass voice or a deep soprano. It is difficult to avoid the conclusion that this and the like associations are fundamentally based, that there are, as an acute French philosophic student of music, Dauriac (in an essay 'Des Images Suggérées par l'Audition musicale'[132]), has expressed it, 'sensorial correspondences,' as, indeed, Baudelaire had long since divined[133]; that the motor image is that which demands from the listener the minimum of effort; and that music almost constantly evokes motor imagery.[134]

The association between high notes and physical ascent, between low notes and physical descent, is certainly in any case very fixed.[135] In Wagner's Lohengrin, the ascent and descent of the angelic chorus is thus indicated. Even if we go back to the early composers, the same correspondence is found. In Purcell it is very definite. In Bach—pure and abstract as his music is generally considered—not only this elementary association, but an immense amount of motor imagery is to be found; Bach shows, indeed, a curious pre-occupation in translating the definite sense of the words he is musically illustrating into corresponding musical terms; the skill and subtlety with which he accomplishes this, can often, as Pirro and Schweitzer have shown, be appreciated only by musicians.[136] It is sometimes said that this is 'realism' in music. That is a mistake. When the impressions derived from one sense are translated into those of another sense, there can be no question of realism. A composer may attempt a realistic representation of thunder, but his representation of lightning can only be symbolical; audible lightning can never be realistic.

Not only is there an instinctive and direct association between sounds and motor imagery, but there is an indirect but equally instinctive association between sounds and visual imagery which, though not itself motor, has motor associations. Thus Bleuler considers it well established that among colour-hearers there is a tendency for photisms that are light in colour (and belonging, we may say, to the 'high' part of the spectrum) to be produced by sounds of high quality, and dark photisms by sounds of low quality; and, in the same way, sharply-defined pains or tactile sensations, as well as pointed forms, produce light photisms. Similarly, bright lights and pointed forms produce high photisms, whole low photisms are produced by opposite conditions. Urbantschitsch, again, by examining a large number of people who were not colour-hearers, found that a high note of a tuning-fork seems higher when looking at red, yellow, green, or blue, but lower if looking at violet. Thus two sensory qualities that are both symbolic of a third quality are symbolic to each other.

This symbolism, we are justified in believing, is based on fundamental organic tendencies. Piderit, nearly half a century ago, forcibly argued that there is a real relationship of our most spiritual feelings and ideas to particular bodily movements and facial expressions. In a similar manner, he pointed out that bitter tastes and bitter thoughts tend to produce the same physical expression.[137] He also argued that the character of a man's looks—his fixed or dreamy eyes, his lively or stiff movements—correspond to real psychic characters. If this is so we have a physiological, almost anatomical, basis for symbolism. Cleland,[138] again, in an essay, 'On the Element of Symbolic Correlation in Expression,' argued that the key to a great part of expression is the correlation of movements and positions with ideas, so that there are, for instance, a host of associations in the human mind by which 'upward' represents the good, the great, and the living, while 'downward' represents the evil and the dead. Such associations are so fundamental that they are found even in animals, whose gestures are, as Féré[139] remarked, often metaphorical, so that a cat, for instance, will shake its paw, as if in contact with water, after any disagreeable experiences.

The symbolism that to-day interpenetrates our language, and indeed our life generally, has mostly been inherited by us, with the traditions of civilisation, from an antiquity so primitive that we usually fail to interpret it. The rare additions we make to it in our ordinary normal life are for the most part deliberately conscious. But so soon as we fall below, or rise above, that ordinary normal level—to insanity and hallucination, to childhood, to savagery, to folk-lore and legend, to poetry and religion—we are at once plunged into a sea of symbolism.[140] There is even a normal sphere in which symbolism has free scope, and that is in the world of dreams.

Oneiromancy, the symbolical interpretation of dreams, more especially as a method of divining the future, is a widespread art in early stages of culture. The discerning of dreams is represented in the Old Testament as a very serious and anxious matter (as in regard to Pharaoh's dream of the fat and lean cattle), and, nearer to our time, the dreams of great heroes, especially Charlemagne, are represented as highly important events in the mediæval European epics. Little manuals on the interpretation of dreams have always been much valued by the uncultured classes, and among our current popular sayings there are many dicta concerning the significance, or the good or ill luck, of particular kinds of dreams.

Oneiromancy has thus slowly degenerated to folk-lore and superstition. But at the outset it possessed something of the combined dignities of religion and of science. Not only were the old dream interpreters careful of the significance and results of individual dreams, in order to build up a body of doctrine, but they held that not every dream contained in it a divine message; thus they would not condescend to interpret dreams following on the drinking of wine, for only to the temperate, they declared, do the gods reveal their secrets.[141] The serious and elaborate way in which the interpretation of dreams was dealt with is well seen in the treatise on this subject by Artemidorus of Daldi, a native of Ephesus, and contemporary of Marcus Aurelius.[142] He divided dreams into two classes: theorematic dreams, which come literally true, and allegorical dreams. The first group may be said to correspond to the modern groups of prophetic and proleptic or prodromic dreams, while the second group includes the symbolical dreams which have of recent years again attracted attention. Synesius, who lived in the fourth century, and eventually became a Christian bishop without altogether ceasing to be a Greek pagan, wrote a very notable treatise on dreaming, in which, with a genuinely Greek alertness of mind, he contrived to rationalise and almost to modernise the ancient doctrine of dream symbolism. He admits that it is in their obscurity that the truth of dreams resides, and that we must not expect to find any general rules in regard to dreams; no two people are alike, so that the same dream cannot have the same significance for every one, and we have to find out the rules of our own dreams. He had himself (like Galen) often been aided in his writings by his dreams, in this way getting his ideas into order, improving his style, and receiving criticisms of extravagant phrases. Once, too, in the days when he hunted, he invented a trap as a result of a dream. Synesius declares that attention to divination by dreams is good on moral grounds alone. For he who makes his bed a Delphian tripod will be careful to live a pure and noble life. In that way he will reach an end higher than that he aimed at.[143]