Labor and rest, city and country life, social discourse and mere play, entertainment in solitude, now with prose, now with poetry, sometimes with philosophy, sometimes with mathematics, all those changes of activity strengthen the mind.
I used to know a young philosopher named John. I say young because he was fresh out of graduate school with a PhD. We tend to think of a philosopher as a gray haired, bearded old professorial type with a system of thought summed up from a lifetime of pondering. John was an exception to that picture, as I'm sure there are others. He was a follower of the English philosopher Alfred North Whitehead, an empiricist and mathematician.
The remarkable thing about John was his ability to completely focus his mind on whatever issue interested him at the time. He could address any topic: astronomy, the economy, poetry, cooking or football, with the same intense concentration. He was curious about everything. He was also very passionate about things he was for or against, but he always had good, sound, well thought out reasons for his opinions. He also had a good sense of humor and play.
I think John's secret was that his mind didn't wander. Nothing in his head interfered with what he was thinking about at the time. But he wasn't the slightest bit critical or judgmental toward people whose minds did wander, such as myself.
John had a girl friend at the time who was my sister-in-law. The four of us would hang around and do things together. He was a pleasure to be with, although often a little intimidating. One always knew that clockwork mind of his was ticking on some issue that had attracted his attention even if he was silent.
We were driving somewhere one day and I posed the following problem:
A guy goes into a gambling hall, pays $4 to get in, doubles his money and pays $4 to get out.
He goes into a second one, pays $4 to get in, doubles his money and pays $4 to get out.
He goes into a third one, pays $4 to get in, doubles his money and pays $4 to get out.
He goes into a fourth, pays $4 to get in, doubles his money and pays $4 to get out.
When he leaves the fourth gambling hall he has no more money. How much money did he have when he started?
John immediately started from the end and calculated, adding and subtracting as he went. He stopped only once to ask me if there was a fourth gambling hall. When I said there was he went ahead and gave the correct answer. It took him way less than a minute.
John, I wish you great happiness wherever you are.