I mean, "essential" really is in the eye of the beholder, which makes the whole point moot, especially as this quote is often brought up in cases where the "essential-ness" of what is being curtailed is highly debatable.

This isn't an academic argument, either. Just look at the gun debate in the US. Many argue that any curtailment of the right to bear arms, from a pistol to a bazooka, is an infringement of essential liberty. Many others strongly disagree that the right of individuals to own high-powered firearms is an essential liberty.

Of course it's in the eye of the beholder. The quote is just one man's subjective opinion. It's a pretty way of stating one person's opinion as to the relative importance of essential liberty and safety which many people agree with.

It's a matter for debate what liberties are essential and different people believe different things.