Distinguishing the essential from the nonessential is one of the most fundamental kinds of interpretive judgment. It has to do with what we treat as important, which provides the justifying frame for all our more particular values.
Just what is essential is often regarded as necessary and as somehow pre-given. I think rather that judgments of essentiality are relative to the complete context in which they occur, and are always provisional based on our current understanding. They guide our interpretation of what is right and what is true. But on all concrete matters, the last word is never said.
Determinations of what is essential are neither crudely objective nor crudely subjective. They are not simply given to us, and neither are they subordinate to our arbitrary will (if indeed there were such a thing). They have to do with how things are interrelated.
I identify the essential with “meaning” or ethical substance, as contrasted with mere logistics. Logistics have to do with the arrangement of accidents.
We cannot live on essence alone. Some involvement with worldly logistical details is unavoidable, and whatever we do ought to be done well in a comprehensive sense. There is even a deep lesson from Hegel that from what begins as accidental, something essential may emerge.
The Postmodern Peripatetic 