Essence -- Radiating with the energy of who you really are. Your core essence — that which created your DNA and incarnation circumstances. According to the Taoist I Ching, evolution occurs on the path of "reverse alchemy," the path of "returning to the Tao." Evolution does not necessarily occur by perpetual attunement to the Tao. Daisies, spiders and viruses live perfectly attuned to the Tao, never deviate from it, but don't have the potential for individual evolution that human beings possess. We are born in touch with our essence, but relentless programs of conditioning work to separate us from our original essence. However, if we are able to travel the difficult path of reverse alchemy, undo the many layers of conditioning and restore our original essence, then we will be evolved.
There are many definitions of essence. From Wikipedia article on essence: "In philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without which the substance can still retain its identity." This same article surveys many philisophical versions of essence, but unfortunately omits the Taoist/I Ching version that I am using.