Analysis of Substitution

WHEN some beloved voice that was to you
Both sound and sweetness, faileth suddenly,
And silence, against which you dare not cry,
Aches round you like a strong disease and new--
What hope ? what help ? what music will undo
That silence to your sense ? Not friendship's sigh,
Not reason's subtle count; not melody
Of viols, nor of pipes that Faunus blew;
Not songs of poets, nor of nightingales
Whose hearts leap upward through the cypress-trees
To the clear moon; nor yet the spheric laws
Self-chanted, nor the angels' sweet ' All hails,'
Met in the smile of God: nay, none of these.
Speak THOU, availing Christ !--and fill this pause.