The implications of "essence/function" and "body/its functions" are similar, that is, both paradigms are used to point to a non-dual relationship between the two concepts. There is a subtle but crucial difference, however, between the two models, "essence/function" and "body/its functions".
If we look at our Chan model of right hemisphere operations, we find that Essence and Function are mentioned. Essence is the Sensory Awareness that separates Awareness into its sensory divisions, where in the right hemisphere the Observing (not an Identity observer) is eventually apparent (without content), allowing eventually right-hemisphere body functionality, while Function which arises from Original Awareness generates the possible expression of Benevolent Affect.
The Contemplation upon FUNCTION rests upon a full understanding of both the base of ESSENCE -as the information of the operation of the sense doors signaling the contact that produces all ILLUSIONS of the Samsaric Truth- and FUNCTION as the Non-Dual origin of "Suchness".
With these two clear, then a last conceptualization experience can be generated which allows the FUNCTION OF FUNCTION to be pierced.