Gustav Klimt  - Adam and Eve Egon Schiele - Half-draped Woman
Klimt and Schiele are both very popular. They lived in the same part of the world, at about the same time. (For some purposes, it probably wouldn't hurt to put Georg Grosz in the same pot.) It's worthwhile to ask what connection their popularity has with their importance as art, or their importance for us in the history of art, or their importance then or now as general history.

Many of their most popular works are female nudes. Eric Hobsbawm (of all people!) points out that the female 'art-nude' has served some members of extremely middle class societies as a respectable way of getting the same satisfaction that some others get from pornography. Is it a coincidence that both Klimt and Schiele tend to unnaturally emphasize the women's nipples? You probably couldn't sell that story to Desmond Morris.

But they have a lot more in common than that. What significance does their tendency to social criticism have tens of years later? For the history of art, probably not much. In the light of much that happened later, though, many have wondered what significance the decadence of Early-Twentieth-Century Central Europe had for general history.

And how about the way that both of them turn their subjects, especially the female nude, into swirling surface designs? There's too much of this tendency in painting of about this period for that to be a coincidence, or merely a stylistic feature of a single movement.
Alphonse Mucha  - Waverly Cycles
This is one of the great meta-patterns of Late-Nineteenth- and Early-Twentieth-Century painting. What significance does this have in the longer history of art, or in the history of society? I could point out a parallel, but we mustn't make too much out of coincidences.

Spaces, not commas, please!