It's important to know that if you are dealing with shadows.
The sun is the most parallel light source because it is so far away.
Every once in a while, when the audience is expecting to see one thing, you have to show them something else.
I hope I'm still shooting when I'm 80.
With today's fast films, you can light the way your eye sees the scene. You can abuse the film and create subtleties in contrast with light and exposure, diffusion and filters. That's what makes it an art.
But you know you haven't done it all because you know everything keeps evolving and changing; and you know you can evolve with it if you grow and develop as a human being.