In following the march of human intellect in the past, we are struck by the slowness with which thought and speech co-operated. As long as our ancestors had no occasion to speak of the action of covering a surface with a liquid or soft substance, they did not possess the word var = to cover; “the name of colour in Sanscrit is varna, clearly derived from this word; and not till the art of painting, in its most primitive form, was discovered and named, could there have been a name for colour.” For some time they continued to view various objects differently coloured without distinguishing the tints; it is well known that the distinction of colours is of late date; our ancestors gazed on the blue sky, or the green trees, as in a dream, without recognising blue or green, as long as they lacked words to define the two colours, and some time elapsed before they particularised the colours by giving each its proper title.

We speak of the seven colours of the rainbow, because the intermediate tints elude us; the ancients acted much in the same way, Xenophanes speaks of the rainbow as a cloud of purple, red, and yellow; Aristotle also speaks of the tri-coloured rainbow, red, yellow, and green; and Democritus seems only to have mentioned black, white and yellow.

Does this indicate that our senses have gradually become more acute and accurate? No, no one has asserted that the sensitiveness of the organs of sense was less thousands of years ago than it is now; the sensation has not changed, but “we see in this evolution of consciousness of colour how perception goes hand in hand with the evolution of language, and how, by a very slow process, every definite concept is developed out of an infinitude of indistinct perceptions.”[56]

The names of colours have not been applied arbitrarily, any more than the names given to divinities. Blue, for instance, owes its origin to the visible results of violence, or of an accident; the science of etymology shows us that the Old Norse words, blár, blá, blatt, which now mean blue, meant originally the livid colour of a bruise. Grimm traces these words back to the Gothic bliggvan, to strike; and he quotes as an analogous case the Latin cæsius—a bluish grey, from cædere, to cut. If the assertion that blue and green are rarely mentioned until a late date be correct, it would follow that they had been worked out of an infinity of colours before they took their place definitely as the colour of the sky and the colour of the trees and grass.

As we trace etymology to its source, we see how man’s perception was confused at first. From the Sanscrit root ghar, which has many different meanings, such as to heat, to melt, to drip, to burn, to shine, come not only many words—heat, oven, warmth, and brightness, but also the names of many bright colours, all varying between yellow, green, red, and white. But the most striking example is afforded by the Sanscrit word ak-tu. Here we have the first instance of the uncertainty in the meaning of the names of colours which pervades all languages, and which can be terminated at last by scientific definition only. This word has two opposite meanings—a light tinge or ray of light, and also a dark tinge, and night; this same word in Greek, ak-tis, means a ray of light. Thus, whilst ideas are not definitely named, even the most simple, such as those of white and black, are not realised; philosophers have long known this, but the learned in physical science seem only recently to have drawn attention to the fact. Virchow was the first to make the following assertion: “Only after their perceptions have become fixed by language, are the senses brought to a conscious possession and a real understanding of them.”[57]

Surgeons have explained that the faculty of sight proceeds from the movement of an unknown medium, which in the case of light has been called ether, this strikes the retina, and is conveyed to the brain by the optic nerve; “but what relation there is between the effect, namely, our sensation of red, and the cause, namely, the 500 millions of millions of vibrations of ether in one second, neither philosophy nor physical science has yet been able to explain.”[58]

We are able to picture to ourselves the difficulties which assailed man in his efforts to express his impressions in primitive times, since we find ourselves at times struggling with the same difficulties, and there are occasions when we struggle in vain, we do not conquer the difficulty.

Sensations which are subjective and personal are of all others the most difficult to define, since we lack words to express what is from its nature purely personal; and yet we have frequently occasion to mention them, how can we best express ourselves? As the required word does not seem forthcoming we have recourse to metaphor, and almost unconsciously we use terms borrowed from external phenomena connected with the sense of hearing, of smelling, and of tasting, and which for the most part are acts or conditions in the domain of the sense of sight. Our old acquaintances the roots, whose meanings are to cut, to pinch, to bite, to burn, to hit, to sting, to soften, having formed the base of the adjectives sharp, sweet, keen, burning, we use these to describe certain sensations. We do not know how better to particularise a physical pain than by comparing it to something that tears, cuts or stings. But if certain physical ills, certain colour perceptions, certain impressions of sharpness, sweetness and heat experienced when tasting various foods find metaphorical expression in external acts, there still remains a whole category of simple ideas for which no words can be found. There are certain sensations of taste which cannot be expressed in words. Yesterday I ate a pear, to-day I have eaten a peach; I am quite capable of distinguishing the special flavour of each, but finding nothing in the world of facts with which to compare them, I am without words to apply to them, and it would be as impossible for me to convey an idea of the flavour to any one who had never eaten a pear or a peach as to make any person understand if I spoke in a language which was unknown to him.

Since all words that succeed in expressing our sensations are drawn from external phenomena, we are in a position to know the origin and historic past of these words. But I cannot thus easily foresee even the near future of some of these words. The sound of the clarionet and that of the hautbois, the whistling of the wind, the whisper of the waves, the yellow of the straw and that of the lemon, the green of the emerald and the blue of the sky, all characterise objects belonging to the material world; but if these words: clarionet and hautbois, wind and waves, straw and lemon, emerald and sky, which alone enable us to define clearly to our minds certain sounds and certain colours were lacking in our vocabulary, I do not know how a musician could have composed a symphony, or an artist painted his picture, although the creation of both works of art proceeds equally from personal inspiration invisible to the eye.

The tie that binds thought to speech has been alternately acknowledged and forgotten; if Plato believed that the origin of language was the imitation of the voices of nature (an error which weighed heavily on humanity during the space of two thousand years), he also knew that words are indispensable to man for the very formation of thought. Abelard was more explicit on this point, he said: “Language is generated by the intellect, and generates intellect.” Hobbes understood so well that language was meant first of all for ourselves, and afterwards only for others, that he calls words, as meant for ourselves, notæ, and distinguishes them from signa, the same words as used for the sake of communication, and he added: “If there were only one man in the world he would require notæ.”[59] The close connection between thought and speech cannot be more clearly or concisely expressed.