Analysis of Let me be to Thee as the circling bird

Let me be to Thee as the circling bird,
Or bat with tender and air-crisping wings
That shapes in half-light his departing rings,
From both of whom a changeless note is heard.
I have found my music in a common word,
Trying each pleasurable throat that sings
And every praised sequence of sweet strings,
And know infallibly which I preferred.

The authentic cadence was discovered late
Which ends those only strains that I approve,
And other science all gone out of date
And minor sweetness scarce made mention of:
I have found the dominant of my range and state -
Love, O my God, to call Thee Love and Love.