Polyphonic music presents to the student so complex a form as to require the aid of material imagery in order to help the mind to a proper conception of it. Perhaps no more misleading idea has been advanced than that which makes use of the Gothic cathedral as an illustration of polyphonic form. It is true that in its multiplicity and yet inter-relation of details the cathedral expresses one of the dominant ideas of polyphonic music; but here the likeness fails. A nicer perception of the subject may be gained by comparing _polyphonic music_ to the _foundation of a Gothic cathedral_, strong and massive in construction, of utmost need to the permanence of the building, but entirely lost sight of in a general view of the whole structure; the importance of the comparison being the likeness of the complex and highly-developed superstructure to monophonic or modern music, seemingly so independent of what lies beneath, but in reality, dependent upon, and intimately connected with the established basis. Only in this way can we apprehend the real value of the polyphonic foundation to our superstructure of modern music; but for that foundation our modern music must have remained in its infancy for centuries to come. No freedom of artistic expression can be gained until absolute command of the material to be used has been obtained, and the principles thoroughly assimilated by the artist. =Polyphony and Monophony Contrasted=.—In the concrete, _polyphonic_ music may be represented by a series of lines representing _separate_ and distinct _melodies_; though a principal melody is always used, it is not supported by chords of harmonic structure but by other melodies, or transpositions of the same melody, so used as to contrast with and support each other. Polyphonic music was essentially melodic, and, as has been very aptly stated, is to be thought of horizontally. Monophonic music might best be represented by one horizontal line supported at intervals by short, perpendicular lines. In this case the horizontal line represents the only distinct melody, and the perpendicular lines the subordinate or harmonic support or accompaniment. The following example illustrates the process of using the same melody to furnish the principal idea and also the accompanying support, the latter being at the same time simply a transposition of the original melody. [Music: Lento 1st Voice 2d Voice 3d Voice] Polyphonic Style. Bach Fugue. Subject (or melody) enters in measure one; again, transposed to the fourth below in measure three, and one octave below in measure ten. Enough is cited to show the horizontal structure of polyphonic music. To present the idea more clearly and for the sake of contrast, a melody with accompaniment is shown in the next illustration, giving a single melody with the subordinate chord accompaniment, the chords in whole notes indicating the harmonic structure or basis. [Music]