Who was Van Gogh writing when he wrote : " It is a kind of painting that rather changes in character , and takes on a richness the longer you look at it . " ?
This was a blow to van Gogh 's confidence as an emerging artist , and he wrote back to his friend , " you ... had no right to condemn my work in the way you did " ( July 1885 ) , and later , " I am always doing " what I ca n't do yet " in order to learn how to do it . "