Criminal Minds, Season 5

[Reid reads a series of books outdoors while next to Eric, who is playing chess against himself]

Eric:
We missed you out here.

Reid:
Oh thank you. Thanks, I uh, I had to take a little break.

Eric:
How come?

Reid:
Used to play with a co-worker friend of mine, he's probably the best mind I ever went up against. One day he just, decided that he didn't want to play anymore.

Eric:
So you gave up too?

Reid:
Just the opposite. I attempted to play through every permutation of moves on a chess board.

Eric:
That's an infinite number of games.

Reid:
It's not infinite. It's just, it's exponentially large.

Eric:
You couldn't have played through them all.

Reid:
There's an average of forty moves per chess game and I'll tell you something. The more I play, the more I realize that every single match, every single chess game is really just a simple variation on the exact same theme, you know? Aggressive openings, patient mid-game, inevitable checkmate, and I realized when my friend quit he was tired of repeating the exact same patterns and expecting a different outcome.

Eric:
So you have a life time of chess strategy in your head and you're just sitting on it?

[Reid's phone rings]

Reid:
I still use it, I just uh, I apply it differently. I have to go, it's good seeing you.