The world was only just beginning to connect this mysterious property of amber with the thunder and lightning, and however still and heavy the air might have been, it would have been impossible for the lexicographer to describe it by that word. Or again, supposing the letter had said nothing about a storm, but that it had described a conversation between Garrick and Goldsmith which was carried on “at high tension”, we should still have little hesitation in pronouncing it to be a forgery. The phrase “high tension”, used of the relation between human beings, is a metaphor taken from the condition of the space between two electrically charged bodies. At present many people who use such a phrase are still half-aware of its full meaning, but many years hence everybody may be using it to describe their quarrels and their nerves without dreaming that it conceals an electrical metaphor——just as we ourselves speak of a man’s “disposition” without at all knowing that the reference is to astrology.[1] Nevertheless by consulting an historical dictionary it will still be possible to “date” any passage of literature in which the phrase occurs. We shall still know for certain that the passage could not have been written in a time before certain phenomena of static electricity had become common knowledge. Thus, the scientists who discovered the forces of electricity actually made it possible for the human beings who came after them to have a slightly different idea, a slightly fuller consciousness of their relationship with one another. They made it possible for them to speak of the “high tension” between them. So that the discovery of electricity, besides introducing several new words (e.g. _electricity_ itself) into our everyday vocabulary, has altered or added to the meaning of many older words, such as _battery_, _broadcast_, _button_, _conductor_, _current_, _force_, _magnet_, _potential_, _tension_, _terminal_, _wire_, and many others.