Full Idea
It is the notion of 'immediate' ground that provides us with our sense of a ground-theoretic hierarchy. For any truth, we can take its immediate grounds to be at the next lower level.
Gist of Idea
An immediate ground is the next lower level, which gives the concept of a hierarchy
Source
Kit Fine (Guide to Ground [2012], 1.05 'Mediate')
Book Reference
'Metaphysical Grounding', ed/tr. Correia,F/Schnieder,B [CUP 2012], p.51
A Reaction
Are the levels in the reality, the structure or the descriptions? I vote for the structure. I'm defending the idea that 'essence' picks out the bottom of a descriptive level.