The students of languages (philologists) tell us that they are unable to trace with certainty any common features in all the languages of mankind. They cannot even find any elements common to all the Caucasian languages. They find over great areas groups of languages which have similar root words and similar ways of expressing the same idea, but then they find in other areas languages which appear to be dissimilar down to their fundamental structure, which express action and relation by entirely dissimilar devices, and have an altogether different grammatical scheme.