John Laskaris’s short Treatise on Byzantine Music Theory is of particular musicological interest; it’s titled as follows: This is another modulation of the musical art, more wisely devised and more exact in every detail, worked out and drawn up by John Laskaris. It is both contrary to the first one and not contrary. It is [appears] contrary to the first one for those [readers] who did not understand it as it was written; but for those who possess full artistic and exact knowledge of it, it is rather a verification and a supplement, as it revealed itself as a great delight by virtue of [a command of] its skill, having clearly indicated its peculiarities by showing the whole essence and movements of the four [main] Modes and of their four Plagal Modes, both in ascent and descent.
Indeed, in above Theoretical Treatise [which is accompanied by a very interesting diagram] is being describing both ascending movements of Plagal and descending movements of Authentic Modes; and therefore the creation of some peculiar versions of same Modes; like, on the one hand, di-phonic, tri-phonic and tetra-phonic ones; and, on the other, Mediant and Para-Mediant Modes, Plagal and Para-Plagal ones: In the ascent of a Mode from the Plagal ones, one obtains the di-phonic, tri-phonic and tetra-phonic ones and these terminate into their Plagal ones and other [Modes]. In descent from the Main Modes, these result in Mediant and Para-Mediant Modes, Plagal and Para-Plagal ones and these terminate on their own fundamentals.
In the present paper I reread the said already very well-known Theoretical Treatise, while preparing its Critical Edition (an effort never undertaken till now); there are some very interesting musicological remarks coming out from such a rereading, through which one could not only correct some misunderstood points of the Treatise, but most of all comprehend the entire musical philosophy (both the theoretical and the practical one) of its writer.
