I am struggling to understand the following sentence in the third paragraph in Chapter 1 of The Moon and Sixpence:
And when such as had come in contact with Strickland in the past, writers who had known him in London, painters who had met him in the cafes of Montmartre, discovered to their amazement that where they had seen but an unsuccessful artist, like another, authentic genius had rubbed shoulders with them there began to appear in the magazines of France and America a succession of articles, the reminiscences of one, the appreciation of another, which added to Strickland's notoriety, and fed without satisfying the curiosity of the public.
You can find this sentence here.
I began to feel confused when seeing this part:
..., authentic genius had rubbed shoulders with them there began to appear in the magazines...
Initially, it looks to me wrong that "had rubbed" and "began" appear in the same sentence because they are both verbs that are used as predicates.
However, after looking closer, it then looks like the real subject of this part of the whole sentence is the very long "where": where they had seen but an unsuccessful artist, like another, authentic genius had rubbed shoulders with them there.
Is my break-down of this part correct?
But even if I'm correct above, I'm still confused why there are two "had done" parts: had seen and had rubbed. I think there must be two parallel subjects. The first subject seems to be "they" which refers to all those famous writers or painters; the second one seems to be "authentic genius". Am I right?? But why is there not an "and" to connect them?