Susanna and Peter Quince

Clavier-depending on the language any sort of keyboard instrument or a specific keyboard instrument.

Just as my fingers on these keys
Make music, so the self-same sounds 
On my spirit make a music, too. 
Music is feeling, then, not sound; 
And thus it is that what I feel, The relationship between the music and the writing and their connection to emotions is interesting. Is he expressing his emotion in his music or creating emotion by playing music?
Here in this room, desiring you, Desiring who?

Thinking of your blue-shadowed silk, 
Is music. It is like the strain 
Waked in the elders by Susanna;

Of a green evening, clear and warm, 
She bathed in her still garden, while 
The red-eyed elders, watching, feltWhy are they red-eyed?

The basses of their beings throb 
In witching chords, and their thin blood 
Pulse pizzicati (Light plucking sound) of Hosanna (Which as I understand to be a cry for help in the archaic sense and a shout of praise in more recent usage, such as in hymns).

II

In the green water, clear and warm, 
Susanna lay. 
She searched 
The touch of springs, 
And found 
Concealed imaginings. 
She sighed, 
For so much melody.

Upon the bank, she stood 
In the cool 
Of spent emotions. 
She felt, among the leaves, 
The dew 
Of old devotions.

She walked upon the grass, 
Still quavering. 
The winds were like her maids, 
On timid feet, 
Fetching her woven scarves, 
Yet wavering.

A breath upon her hand 
Muted the night. 
She turned -- 
A cymbal crashed, 
Amid roaring horns. The music becoming abruptly harsh

III

Soon, with a noise like tambourines, 
Came her attendant Byzantines.

Against the elders by her side;

And as they whispered, the refrain 

Was like a willow swept by rain. Beautiful imagery, but it confuses me
Anon, their lamps' uplifted flame 
Revealed Susanna and her shame. Indication that something did indeed happen, rather than Susanna remaining resistant as in the Biblical story

And then, the simpering Byzantines 
Fled, with a noise like tambourines.

IV

Beauty is momentary in the mind -- 
The fitful tracing of a portal; 
But in the flesh it is immortal. Beauty momentary in the mind, eternal in the body-this is opposite what is expected

The body dies; the body's beauty lives. 
So evenings die, in their green going, 
A wave, interminably flowing. Wave of time
So gardens die, their meek breath scenting 
The cowl of winter, done repenting. 
So maidens die, to the auroral 
Celebration of a maiden's choral.

Susanna's music touched the bawdy strings 
Of those white elders; but, escaping, 
Left only Death's ironic scraping. 
Now, in its immortality, it plays 
On the clear viol of her memory, 
And makes a constant sacrament of praise.

  This poem appears to be about beauty, and specifically about the beauty and immortality of art, such as poetry, music or the literature of the Bible. The narrator of the poem seems to make a certain point of separating the passion he feels for his type of beauty and the lust of the Elders for Susanna's beauty. The Elder's  lust, aroused by "Susanna's music" , the beauty of her body, is on an instinctive level ,and is fleeting and doomed to nothing, while Peter Quince's idea of true beauty is to create something from his feelings that will last in "in its immortality" a "constant sacrament of Praise".  A reader of this poem and the Bible can make an instant connection with the beauty and immortality, spoken of, and the great piece of art that the poet drew his inspiration from.