Give that year that Van Gogh wrote to his brother about the Portrait of Dr. Gachet .
In a letter from May 20 , 1890 , Van Gogh wrote , " I have seen Dr. Gachet , who made the impression on me of being rather eccentric , but his experience as a doctor must keep him balanced while fighting the nervous trouble from which he certainly seems to me to be suffering at least as seriously as I . "