where does the word 'satst' get used? and what does it mean really?

While reading the poem "Paradise Lost" by John Milton, I came across the usage of the word satst. Can anyone tell me what it means? I can gather what the other words imply, but for this one I needed some clarification.

[...] Dove-like satst brooding on the vast Abyss [...]

Paradise Lost (London, 1674)


Solution 1:

It is an archaic formal second person past tense of "to sit," and should not be used in current English.