Analysis of Sonnet LXXIX: The Monochord

Is it this sky's vast vault or ocean's sound
That is Life's self and draws my life from me,
And by instinct ineffable decree
Holds my breath quailing on the bitter bound?
Nay, is it Life or Death, thus thunder-crown'd,
That 'mid the tide of all emergency
Now notes my separate wave, and to what sea
Its difficult eddies labour in the ground?
Oh! what is this that knows the road I came,
The flame turned cloud, the cloud returned to flame,
The lifted shifted steeps and all the way?—
That draws round me at last this wind-warm space,
And in regenerate rapture turns my face
Upon the devious coverts of dismay?