Again, _India ink_ comes, not from India, but from China. _Indian corn_ comes from America. _Sedan chairs_ had nothing to do with Sedan in France, but probably take their name from the Latin verb _sedere_, "to sit."
In these words, as in many others, we can see that it is never safe to _guess_ the derivation of words. Many of the old philologists used to do this, and then write down their guesses as facts. This caused a great deal of extra work for modern scholars, who will not, of course, accept any "derivation" for a word until they have clear proof that it is true.
Everybody who has thought at all about our ways of speech must have noticed that we are all constantly saying things in a way which is not literally true. We say a child is a "sunbeam in the house;" but, of course, we only mean that she is gay and happy, and cheers every one up by her merriment. Or we describe some one as a "pearl among women," meaning that by her splendid qualities she is superior to most women as a pearl is to common stones.
Or, again, we may read in the newspaper that a statesman "spoke with sudden fire;" by which, of course, we understand that in the course of a calm speech he suddenly broke out passionately into words which showed how keenly he felt on the subject of which he was speaking.
Our language is full of this kind of speaking and writing, which is called "metaphorical." The word metaphor comes from two Greek words meaning "to carry over." In "metaphorical" speech a name or description of one thing is transferred to another thing to which it could not apply in ordinary commonplace language.
By means of metaphors we express more vividly and strikingly our feelings on any subject. We draw our metaphors from many different sources. Many of them naturally come from Nature, for the facts of Nature are all around us. We speak of a "sea of trouble" when we feel that the spirit is overwhelmed by sadness so great that it suggests the vastness of the sea swallowing up all that it meets. Or we speak of a "storm of anger," because what takes place in a person's soul in such a state is similar in some way to the confusion and force of a storm in Nature. Again, an expression like a "torrent of words" is made possible by our familiarity with the quick pouring forth of water in a torrent. By this expression, of course, we wish to suggest a similar quick rushing of words. Other expressions of this kind are "a wave of anguish," the "sun of good fortune," and there are hundreds of which every one can think.