Not sure how many art historians hang out here but I'm curious to know.
Perhaps I'm being too cynical but I'm imagining someone buying his works on the cheap, suddenly "discovering" his genius and promoting his works for their own gain, kind of like a penny stock pump on wall street.
Art Historian! I am going to assume you mean Van Gogh.
Van Gogh was a revolutionary painter for his time, and indeed it can be said that he was too early! He was part of the post-impressionist movement which was an almost meta movement. To understand art history, everything must be taken in context. For a rough outline, painters had been painting naturalistic forms for hundreds of years. Then come the impressionists who believed that art was subjective, and that the motif simply made an impression on the viewer. They were already breaking away from traditional forms of representation in form and colour. Following comes Van Gogh who then breaks even further away from traditional forms and approaches abstraction, as can be seen here here and here. This was very frowned upon by contemporary art critics, and combined with the fact that Van Gogh died at a very young age, prevented him from seeing fame.
In the 20th century, there was a series of rapid movements in art called the avant-garde movements. These movements went against traditional forms of representation and brought out new theories of "art for the sake of being art." During this time, Van Gogh's works became much more influential, as they were viewed as non-traditional forms of representation, and were supported by the avant-garde. Van Gogh was truly before his time, and if he had lived on, we would have seen him become famous in the early 20th century.
Edit. Forgot some sources. I recommend the following books:
Cezanne and the End of Impressionism
While they are not specifically about Van Gogh, they do mention him in context which helps immensely. (Art must be studied in context).
