In the Beethoven Mass a Preludium for orchestra is introduced, to fill in the interval while the celebrant is occupied with these silent prayers.  It is an innovation, showing how thoroughly alive Beethoven was to the development of every phase of his subject.  Ordinarily, no provision is made for this by the composer, the organist being permitted the privilege of interpolating hymns like the O Salutaris or the Tantum ergo.  The Preludium is so timed that it ends at the conclusion of the prayer we have quoted, when the sacred elements are in heaven and are about being returned to earth.  It is at this point that the symphonic thought begins, which at the first bar calls to mind celestial harmonies.  Here we have the tone-figure, as in the Lohengrin Prelude, given by the violins and flutes in the highest register, beginning in faintest pianissimo.  At the second bar the melody begins to descend, being augmented in force by the gradual addition of the more powerful instruments as well as voices when the elements are again on earth.  The Lohengrin Prelude has the same idea, but it is developed to a greater extent, with a richer orchestration, the idea being carried to greater length, and rendered more significant in every way, as befits its dramatic character.  In both cases, however, the orchestral figure is introduced by the same instruments, and in much the same manner.

The Mass in D furnishes another instance where the celestial harmonies are introduced to still better purpose than in the Benedictus.  It is in that portion of the Credo, beginning with the Et incarnatus.  The delicate ethereal nature of this music, as indicated by the violins and flutes in the highest positions, is so transcendental, so imbued with spirituality, as almost to evade analysis.  By the magic of Beethoven’s art the impression is conveyed that the listener overhears far-off angel voices from other spheres, when the heavens were opened for the descent of the Son of God to earth.  The instruments give out the merest intimations of sound, scintillations that suggest it rather.  In the opening bars of the movement, just before the introduction of this tone-figure, he uses an ancient ecclesiastical style, the Plagal, a mode that obtained centuries before Palestrina.  Harsh and strident, inharmonious, are the tones, which in the opening Adagio typify the dread, the foreboding and dismay, that can be supposed to have been felt by the Son of God when the time came to give up a beatific state and enter on the actualities of earthly existence.  The sin of the world is already being borne in anticipation.  Suddenly we are in the midst of celestial harmonies, delicate gradations and mergings of tones, subtleties of expression, ethereal, evanescent, that come faintly at first on the senses, giving us revelations of spiritual heights, of transcendent states and conditions of the soul.  Mankind is here afforded a glimpse beyond the veil.  These strains continue until the words et homo factus est (and was made man) are reached.  At this point the melodies are suddenly cut off, the doors are closed, and we are excluded from further participation in things not meant for mortal ears.  A change of tonality and time further accentuates the changed conditions that prevail as the story goes through the events of the crucifixion, death and burial of Christ.[I]