The Essence of an Actor

During one of my drama classes we were asked a question, it simpily stated; "what is the essence of an actor?' Now usually i can come up with some kind of answer to the questions asked in class, but this one had me answer-less. I sat there at my desk pen in hand with a blank page in front of me i could not for the life of me come up with any form of an answer. so i did the typical teenage student thing and googled it. i found count less textbook and dictionary definitions for what the world thought it meant, yet none of these professional interpretations seemed to bee what i wanted, so i asked my friends and family and long story short i came up with nothing, about a week later Iwas watching a movie with my parents and my dad made a comment about one of the actors saying he can't see him playing any other role which reminded me of something that was said in class, which gave me my answer to what the essence of an actor was. my answer it this; the essence of an actor it their ability to blur that line between Actor and Character. its funny to think that after days of questioning people and research I came to such simple interpretation ;)