All the theories that acting is reacting to imaginary circumstances as though they are real, and directing is turning psychology into behavior, those are all stabs at something that can't be taught. All the great actors can't talk about what they do, and they don't want to begin to talk about it. They just do it.
You can always tell gifted and highly intelligent people as they always turn to the past. Any young person who knows anything that happened before 1980, or 1990, or 2000 for that matter, is immediately someone who is intelligent, probably creative, maybe a writer. Nobody who is drawn to the past and learning about the past is not gifted.