brown study

unelmointi puhekieltä A melancholy mood accompanied by deep thought; a moody daydream.
1851, (w), Moby-Dick:

So gathering up the shavings with another grin, and throwing them into the great stove in the middle of the room, he went about his business, and left me in a brown study.

Finding that Holmes was too absorbed for conversation, I had tossed aside the barren paper, and leaning back in my chair, I fell into a brown study. Suddenly my companion's voice broke in upon my thoughts.

But Quatrefages glared at his plate in a brown study.