Is it not conceivable, that each tone is the fusion of a sum of still more primitive elements with the Gestalt qualities bound up therewith?... No conclusive argument can be brought forward even against the possibility that we may not, penetrating ever more deeply in this manner, finally arrive at a single proto-quality, or at least at a single quality-continuum, from out of which distinct contents (colours, tones, Y) are generated by the fusion of distinct combinations with the Gestalt qualities bound up therewith, [so that] one can no longer shrink from the idea that tones and colours might be exhibited as the products of a much higher degree of complication of proto-elements as yet unknown.