Premise: Andries Bonger (20 May 1861 – 20 January 1936), nicknamed "Dries", was Johanna van Gogh-Bonger's favorite brother. Bonger was a friend of his future brother-in-law Theo van Gogh in Paris. It was through Andries that Johanna and Theo met. He also knew Vincent van Gogh who called him André in letters.
Hypothesis: Andries Bonger was a great friend to Vincent van Gogh