Were there another place in England open to me, I would prefer it. Charles Vernon is my aversion, and I am afraid of his wife.
-- Lady Susan (Letter 2)

Importance: This quote immediately establishes that Lady Susan is a scheming hypocrite.

I love to meet he most accomplished coquette in England.
-- Reginald (Letter 4)

Importance: This quote shows how Reginald was warned about Lady Susan early on, yet he still falls for her.

There is exquisite pleasure in subduing an insolent spirit, in making a person pre-determined to dislike, acknowledge one's superiority.
-- Lady Susan (Letter 7)

Importance: This quote allows a glimpse into Lady Susan's twisted psychology.

This project will serve at least to amuse me, and prevent my feeling so acutely this dreadful separation from you and all whom I love.
-- Lady Susan (Letter 7)

Importance: This quote provides the motivation behind Lady Susan's plot: it is ego-driven.

It may also convince us how little the general report of anyone ought to be credited, since no character, however...
-- Reginald (Letter 14)