Tolstoy had some very particular views on art. I'm not sure he held these all his life, but it does seem everything I've read by Tolstoy had these elements. So if his aesthetic theory came to him at mid life or later, he certainly intuitively applied it throughout most of his works. What is his theory? First it should have simplicity. Don't overly complicate it. Second it should get to the core of humanity, especially of a specific central character. Third, art must embrace humanity, so that the art binds people together. Fourth, it must have a moral, a lesson that teaches something noble. Fifth, it must reflect God in some way. Those are the elements that I can remember. There may be more. So with that context, here is a pithy quote that condenses it down to a statement, coming from his book on the subject, "What is Art?"
"Art lifts man from his personal life into the