Stanza 6 Summary

Get out the microscope, because we’re going through this poem line-by-line.

iridescence; in the
inconsistencies
of Scarlatti.

This is where our speaker starts to throw down some really cool stuff. She's bringing out the fireworks.
She revisits the dove-neck, the inconsistency, and Scarlatti. Sweet.
And what does she do with that dove-neck? She amps up the image. Not only is the sun bringing the dove-neck to life, but also now the iridescence (the shiny colors in the feathers) seems to be on fire.
The inconsistency, which earlier in the poem our speaker used to talk directly about the mind, is now being applied to Scarlatti—the composer we were introduced to at the beginning of the poem. And there's fire in those inconsistencies.
Interesting that she should praise the inconsistencies of such a talented and near-perfect composer. Maybe she's suggesting that it's a good thing that the mind isn't boring and predictable all the time.
The speaker creates a swirling, gyroscope-like motion in this stanza that mimics the diversity and activeness of the mind and its ability to make a ton of connections very quickly. Everything is building toward the close of the poem.

Unconfusion submits
its confusion to proof […]

Just when we were swirling happily toward the end of the poem, our speaker jerks us out of our whirlwind with another riddle-like statement.
Unconfusion, first of all, isn't even a word, but we wish it were. Let's say it means the opposite of confusion… so, clarity.
Submit means to give in willingly.
So this statement is phrased in a backwards kind of way. What it means is that in order for unconfusion to be confusion-free, it relies on proof or facts.
This is a nod toward ways in which the mind can be rational. Remember the heart vs. mind part of the poem? The heart is in charge of feelings, but the mind is in command of the facts.

[…] it's
not a Herod's oath that cannot change.

Uh, guys? Who's Herod? Don't worry; Shmoop's got you covered.
Herod was an ancient leader in Judaea. He had a pretty checkered past, and let's just say he wasn't the nicest man-in-charge ever. As history tells it, he couldn't learn from his mistakes, which led to his downfall.
An oath, of course, is a promise.
So what is Herod doing in the last line of this poem about the mind?
Well, Herod may have been unable to change, but the mind is not like him. It can change, and our speaker has been praising that fact throughout the entire poem.
The most jarring part of this last phrase is that it's not set up like all of the others before it. Throughout the poem, our speaker begins the comparisons with "it is," but in the last line she flips things around with "it's not."
This makes us stop and pay attention, especially given the momentum that had been building up to the end of the poem. It's a complete halt that makes us work mentally all the way to the end, which is the perfect way to end a poem about the mind.
And the best part is, this ending means that the mind can learn from its mistakes. Which is awesome news for us normal folks.