Here’s another classic shot of Arnold. If I remember correctly, he used this picture (in Encyclopedia of Modern Bodybuilding) to demonstrate the level of definition he achieved in his deltoids. He’s looking pretty tough here.
As much as I like Arnold, I would not recommend training like he did (hours a day, every day in the gym). Instead I’d recommend natural trainees follow a different strategy, like Reuben Bajada’s Permanent Muscle Program.