Learn English – What does Macbeth mean when he says his heart is “seated”

connotationshakespeare

Here's the quote (from The Tragedy of Macbeth, by William Shakespeare):

This supernatural soliciting
Cannot be ill, cannot be good. If ill,
Why hath it given me earnest of success,
Commencing in a truth? I am thane of Cawdor.
If good, why do I yield to that suggestion
Whose horrid image doth unfix my hair
And make my seated heart knock at my ribs,
Against the use of nature?

The connotations may have changed since it was written, but doesn't the word "seated" evoke the image of the object under discussion being, to all intents, still? As in pretty much motionless? What am I missing?

Best Answer

Oxford English Dictionary

seated, adj.
1. Fixed in position. Obs. or arch.

with that line from Macbeth as its first example