Language Point 23

Wagner had been occupied with the idea of the "Ring" for several years, ... (Para. 4)
Meaning: For several years Wagner busied himself with the idea of composing the "Ring".
be occupied with sth.: be busy with sth.
She was occupied with the cleaning of the big house.

她正在忙于打扫那幢大房子。
I am afraid that you won't be able to see the doctor for he is fully occupied with appointments this afternoon.

恐怕你见不到那位大夫，因为他今天下午的预约已经排满了。