All 4 Uses

essential
in
Pride and Prejudice
(Edited)

"—for I dare not hope," he continued in a lower and more serious tone, "that he is improved in essentials."
p. 226.1

essentials = things that are necessary
In essentials, I believe, he is very much what he ever was.
p. 226.1 *

essentials = the most important ways
If there were anyone that one could apply to with a probability of gaining such a clue as that, it might be of essential consequence.
p. 280.8

essential = important
The letter shall certainly be burnt, if you believe it essential to the preservation of my regard; but, though we have both reason to think my opinions not entirely unalterable, they are not, I hope, quite so easily changed as that implies.
p. 348.5

essential = necessary

Definitions:

(1) (essential)
necessary or important; or a basic and defining part of something
(2) (meaning too rare to warrant focus)