One of the perennial problems in diachronic linguistics is how to reconcile, on the one hand, the Neogrammarian postulate of sound laws operating without exception, and, on the other hand, the embarrassingly numerous irregularities we observe in many languages. On most occasions linguists have attempted to solve the problem by positing interdialectal borrowing or analogical levelling and have largely overlooked the possibility of the gradual diffusion of phonological changes across the lexicon. As a result of the lexical gradualness of sound changes, exceptions may be created either through the incompletion of a sound change, or owing to the conflict of two sound changes overlapping along the time dimension. It is the latter concept that we will attempt to elaborate and illustrate with two sets of data, both from Peking dialect. We have chosen Chinese as a case study for an obvious reason: it is possible in the case of Chinese, like few other cases, to follow sound changes step by step through the phonological dictionaries, rhyme charts and other records compiled at various stages of history. The columns on Tables 1 and 2 contain information taken from the various datable phonological dictionaries.
