Every act of blowing out a candle is functionally equivalent [...] to every other such act; hence the candle-blowing 'wh' is [...] a sign for an act of a single function. The speech sound 'wh' has no singleness [...] of reference. It is a counter in a considerable variety of functional symbols. e.g., 'when', 'whiskey', 'wheel'. A series of candle-blowing sounds has a natural functional and contextual coherence. A series of 'wh'-sounds as employed in actual speech has no such coherence; e.g., the series 'wh(en)', 'wh(iskey)', 'wh(eel)' is non-significant.
- Sapir (1925), a pag.34