I found the words to every thought — Slavery

Dickinson thought of slaves and found she could do nothing. This thought defied her.

I found the words to every thought 1
I ever had-but One-
And that-defies me-
As a Hand did try to chalk the Sun

To Races-nurtured in the Dark-5
How would your own-begin?
Can Blaze be shown in Cochineal-
Or Noon-in Mazarin?
(F.436/J.581)
[1-2] every thought, but One:: she couldn't find words for slavery.
[3] that defies me:: that she found no words for slavery, or slavery the system, challenges and despises Dickinson, for she could do nothing for that.
[4] to chalk:: to make white with a chalk. the Sun:: something glorious.
[5] Races, Dark:: the black slaves living in darkness.
[4-5] chalt, Rark:: to whiten the black so that they can have glorious too, which is unreal as to chalk the Sun.
[7] Blaze:: a violent outburst (OED n.1 3). Cochineal:: the scarlet blood.
[8] Noon:: the brightest time, the justice. Mazarin:: a London common-councilman; so called for his mazarine blue gown (OED n.2 2b); referring the legislation system.