An important factor in understanding the two kinds of presentation is that – seen historically – one or other has at different times moved into the foreground; moreover, that in connexion with the development of music and as a consequence of the continually progressing ‘conquest of the pitch-domain’, a mixing of the two kinds of presentation was arrived at. Here Webern above all follows Adler, who speaks in his book Der Stil in der Musik (1911) of ‘immensely multifarious intermediate and transitional stages from homophonic to polyphonic voice-leading’, of their mixing, of a ‘to and fro rich in variety, … continual exchange of the two basic kinds, homo – and polyphony’ (p. 246). As has already been said, Webern, going beyond this, assumes that the mixing up is caused by a tendency, on the part of the two kinds of presentation, ‘mutually (to) permeate each other more and more’ (Lecture IV).