Why is the sentence "like a firebell in the night, awakened me and filled me with terror" so important in this letter?

The sentence "like a firebell in the night, awakened me and filled me with terror" is very important because of the slavery which was drawing the North and South apart.

Explanation:

Letter was quoted about the question of the slavery where northerners were abolishing the slavery whereas southerners were in support of slavery. "like a firebell in the night, awakened me and filled me with terror" was quoted by Jefferson to the Hiuouri compnuDin.

This question was marked as momentous of the time and let the difference of opinion on the slavery let the separation swift apart between the north and south. Missouri was said to be a slave state, rest to be freed from slavery.