The ancient and eminent Greek philosopher, Aristotle, wrote a book called "Poetics". In this book ,he described in beautiful detail the requisites for fine art inclusive of  the theatre. Some of the things he thought appropriate for the theatre are: 1. Plot 2. Music  3. Character development 4. Spectacle; and, 5. Moral theme. His understanding of what makes good theatre is, without a doubt, a still valid  approach to both the appreciation of and the understanding of the  value of drama whether it is on the stage or on the screen!