"Brown study As I mentioned last time, one of our correspondents asked me whether anything is known about this idiom. My database has very little on brown study, but I may refer to an editorial comment from the indispensable Notes and Queries (1862, 3rd Series/I, p. 190). The writer brings brown study in connection with French humeur brune, literally “brown humor, or disposition,” said about a somber or melancholy temperament." - Maitani