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Prelude to Chapter VIII.
This chapter is upon sound and hearing; and as these subjects had been but desultorily alluded to in the other works, they are treated of at some length on this occasion. It opens with the distinction of bodies into sonorous and insonorous, and after tracing the analogy between the acute and grave, and the sharp and blunt (of touch), it passes by a rapid transition to the voice, which is dwelt upon at some length. The term ἐνέργεια, which had been used in place of ἐντελεχεία, to express the active as opposed to the potential or negative state of the diaphaneity, is again employed here to signify the analogous and contrasting quality of sound. The distinction between the terms is not very apparent now, although this may not have been the case then; for the ἐνέργεια may have conveyed the idea of action in the transition from potentiality, and so have been more expressive of actual, as opposed to virtual light or sound. Thus, if sound be a quality or condition, it
