Let’s start with X. According to Jeff McMahan, here is a detailed description of the daily routine of one great thinker:
There are many anecdotes about the ways in which [X] simplified his life to take as little time as possible away from his work. He ate only twice a day, with almost no variation in what he had at each meal. He ate cold food only, mostly fruits and vegetables without any preparation. Even when he could have had freshly ground coffee with only a minute’s additional preparation, he drank instant coffee, often with water straight from the tap. He sometimes kept a book open on the chest-of-drawers so that he could read while putting on his socks. His speed in reading was phenomenal, in part because his power of concentration was prodigious. Wanting to preserve his mental and physical capacities, he took an hour every evening during his last decade to get vigorous exercise on a stationary bicycle, but never without reading philosophy (or occasionally physics) while furiously pedalling.
Next, let’s consider Y. Via Alex Soojung-Kim Pang, here is a summary of the daily routine of another great thinker:
After his morning walk and breakfast, [Y] was in his study by 8 and worked a steady hour and a half. At 9:30 he would read the morning mail and write letters. At 10:30, he returned to more serious work, sometimes moving to his aviary, greenhouse, or one of several other buildings where he conducted his experiments. By noon, he would declare, “I’ve done a good day’s work,” and set out on a long walk on the Sandwalk …. When he returned after an hour or more, he had lunch and answered more letters. At 3 he would retire for a nap; an hour later he would arise, take another walk around the Sandwalk, then return to his study until 5:30, when he would join his wife, Emma, and their family for dinner.
Now, guess whether X or Y wrote Reasons and Persons and who wrote The Origins of Species.