Blessed be the poet, the artist who knows how to keep alive his sense of wonder.
An actor is one who observes other people all the time, not critically nor judgementaly, but with curiosity. We observe how someone stands, sits and walks. We notice, movements, gestures and facial expressions, actions and reactions. We listen to the voice. Hear tones, pauses, stresses and breath. Those things can tell a story about people. We are trying to read the story so that we can tell a similar story on the stage.
Human beings are endlessly fascinating creatures to observe. There is hardly anything in the universe that is more complicated and in greater variety than the human race.
One of the reasons why we observe people so carefully is just because on the stage nothing is done in general. Everything is specific. There is no such thing as reacting to a rain storm in general. It's how my character reacts to it that matters. And that starts with a sense of wonder. I wonder what this man is really like, this man who depends upon me to give him life?
I was doing an Off-Broadway show years ago, the story took place in a New York City apartment. In one scene I had to look out the window at the weather and see that it was raining. I knew that there were other buildings partially blocking my view so I took that into consideration. My character was hoping to get on a flight out of town and was worried that the rain would interfere with his plans. It was one very short moment in the play.
An actor friend, who had every right to be critical of my performance, came to see it. He enjoyed it and he made mention of that moment and how completely believable it was. "I saw you looking up at that gray and rainy sky and I knew exactly what you were feeling." The fact is the window was right up against the bare wall of the theatre. There was nothing to see out of it. I simply said if I was looking out of an apartment building window at the rain, I wonder what it would look like? I invented it in my own imagination, believed in it and made it come alive.
Describe a storm. The poet writes it, the painter paints it, the actor plays it.