That which exists and the so-called 'essence,' or the existential modality or way that an entity exists, is precisely the same thing - only the human linguistic signifier changes, (from "egg" to "chicken") in order for the human categorisor to keep nominative pace with the concurrently ever-changing, existential partnership of substances and their combinatory states, which impinge upon the totality of the physical nexus and supervenery Gesamtsumme which is its autogenic collaborator

There has been much philosophical discussion concerning which came first - the chicken or the egg? The answer is neither - they are but earlier and later existential modalities of the same thing.
     The real or sentential (ideative) extantal subject is that which equates or corresponds with the entitative object (the nominatum) named by the signifier - the name or noun by which it is identified.
The real or sentential entity that corresponds to the definite article and signifier: " the man" or "the chicken" is the assemblage, or conglomerate of human existential components in their ever-changing states and modalities.

That which the philosophical tradition extrinsically calls "essence" is intrinsically a seething similitude of physical, event-based somatic equivalences that occur to the quantum-based, component mini-entities of which the entity consists. The ongoing internal and external interactions and the totality of their dynamic somatic events and processes inhere to that physical entireness - the named existent subject entity - the man.

A human subject's responses and reactions to the inherent dynamic of its own internal aggregate conflicts and processes, and the impingements and effects of the outer environment, constitute the de facto, perpetually accommodating, corporeal and mental architecture of the entity.

    This existential - essential concordance is so absolute and consummate, that the sum internal and external activity of an entity indistinguishably incorporates and constitutes the entity itself. The linguistically expedient 'naming' of the perceived material 'stasis' of a human entity as 'Bill' or 'Jane' also equals the sum of its existential - essential activities. The processant 'IS' (the BE-word) allows us to sententially discriminate and descriptionally sequestrate certain perceived states and modalities from the totality that is the subject, in order to make challengeable propositions concerning them.