There is a saying in India that language changes every twelve kos. This saying will still hold good if we say language changes every kos, although the amount of change in the latter case will be almost impossible to detect. In spite of this saying, which is correct at bottom, we are apt to believe that our next-door neighbours (if they are not recent strangers) speak exactly the same language as we do. Similarly we also believe that we speak exactly the same language as our parents spoke or our children will speak. But this our belief is not true, for, as a matter of fact, language changes gradually and almost imperceptibly both in time and space. The language of one's neighbours is slightly different from one's own, but when the distance grows and two persons separated by twenty or thirty miles talk together, they are certain to pick up some peculiarities in each other's speech. In the like manner the speech of the children differs from that of the parents, and in the course of a few generations this difference becomes appreciable.