(noun) The inherent nature of a thing or idea.
"The rose's rarest essence lives in the thorns."
"The energy of the mind is the essence of life."
"Every act of rebellion expresses a nostalgia for innocence and an appeal to the essence of being."
"The Essence of Knowledge is, having it, to use it."
"The real glory is being knocked to your knees and then coming back. That's real glory. That's the essence of it."