I think this is what people mean when they say an actor is generous.
Agree 100%. It's so interesting when you know you're seeing something special. For me, at least, I don't really have "actor sense" to always understand what's making it so special, but it's still so clear. I remember having that feeling watching Richard Thomas play Richard II at the Shakespeare Theater Company in '93/'94 (the internet tells me). He just WAS Richard II. Amazing.