Sometimes changes affect languages in a relatively minor way. Natural tendencies, exaggerated by social factors, cause disruptions, then the language restores the equilibrium again. The situation is reminiscent of day-to-day house cleaning or simple weeding in a garden, when minor problems are quickly eradicated.

At other times, however, the problem is not so easily remedied. An apparent therapeutic change can trigger off a set of wholesale shifts in which the various linguistic elements appear to play a game of musical chairs, shifting into each other's places like the participants at the Mad Hatter's tea-party. Sound shifts are better studied than syntactic shifts. In this chapter, therefore, we shall begin by looking at sound shifts. Afterwards, we shall discuss a possible syntactic shift.

Shifting sounds

For the sake of illustration, this section outlines two well-known examples of chain shifts involving sounds, one of consonants, the other of vowels.