Andamento orizzontale e verticale in alcuni aspetti della musica del XX secolo (Horizontal and vertical voice leading in some aspects of 20th century music), in KonSequenz. Dieci anni di musica di frontiera, a cura di Girolamo De Simone, X,8, 2003, pp.10-22.

Many 20th century composers dealt with the issue of systematically blending horizontal and vertical voice leading. In immediately post-tonal music, vertical and horizontal leading often used to menage with various organizing principles; in order to solve the problem, in practice it was necessary to reduce vertically what, for the fact of being horizontal, would develop in  time and to expand horizontally what, for the fact of being vertical and simultaneous, would develop in space. If it is true that rhythm is intersection between space and time, some unifying rhythmic process was necessary, in order to enable a musical construction to develop in time and space according to a unique principle. Can vertical combinations  produce horizontal movement provided with a rhythm arousing spontaneously from them?
Skrjabin’s system allowed a vertical combination to find the logical principle of its moving towards another combination in itself, regardless its level of tension or its function. Thus, it was a system producing its movement from inner propulsion, on the basis of the nature of the combinations arousing from it.  It may be possible to state that the vertical nature of a combination would also produce the horizontal movement of its elements towards new combinations, according to the equation: vertical interval combination = horizontal movement (that is to say matter=energy). If the inner nature of various combinations is at the basis of their following one after the other along the time axis, then the harmonic and vertical aspect prevails over the counterpoint and horizontal one; the latter can be seen as a consequence of the former.

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