Well, it works in context. Selby goes on to talk about the difficulties of obtaining 'catharsis.' Amen.
For those who don't recognize the word, or perhaps don't have a handle on it, a catharsis is a "purification and purgation [sic] of emotions - especially pity and fear - through art or any extreme change in emotion that results in renewal and restoration."
Try to identify a moment when stress pushed you to the edge of a breakdown - and then over that edge, so that you actually went to pieces. Did you feel better afterwards? That's catharsis.
Recall the last time you were at total peace, where the experience you were having was so complete and relaxing that you lacked the will even to remark upon the thoroughness of the experience. That's catharsis too.
For many people, catharsis is something they reach only through the use of recreational drugs. Pot, hash, ecstasy, heroin, Demerol, Vicodin, Percocet . . . these are very effective at producing catharsis because they discombobulate your brain, separating you from your own thought processes. Stress gone. Worries gone. Cognitive processes - distracted. You're at peace. And when you rise from that peace, you get an extra little comfort from the small vacation you've taken - the same 'feel better' that came from going to pieces on your own.
Now, I've never 'done' these drugs. I'm merely providing information based upon reliable sources. I took Percocet when I snapped my quadriceps tendon back in '08; while it did put me to sleep, it gave me these bizarre hallucinations about things floating over the bed - so I didn't finish the proscription. I wouldn't say I was feeling much catharsis from it. I've had a number of very intense cathartic experiences and none of them were associated with the kind of pain the Percocet was only half-managing. But I digress.
Most morality-based groups would prefer you got your cathartic experiences in a way that did not involve the use of drugs. Of course, many of those would also rather you did not get your catharsis through table-top role-playing, so there we are. I would guess it is really up to the reader. Of course, 12% of the American prison population is not made up of people who screamed, "DIE purple jam thing!" before throwing a 20-sided die.
Woah. That would be a world.
Screaming during a game - any sort of excessive emotion, actually - is a means of obtaining a catharsis. It will get on the nerves of other players, however, so we do encourage players to scream in their own heads and to do their best to concentrate on their die-fetish instead. Thus bringing us, at last, to the point of this post:
You can make catharsis happen.
Yes, yes, I know you're bored with the DM's dungeon. I know that you're horribly jaded and savvy. I know you haven't got the spirit to even pick up the die any more, much less give a shit what it rolls. But try, O Brethren, to remember what was working for you when you first played.
It was new, yes? Of course it was. Back then, you could count on the natural chemicals in your body, the hormonal juice that always gets rolling when you're forced to deal with something unknown. You don't know what the die will roll. You don't know what it will mean. Wow, wasn't it all kewl.
Those days are past now. You'll have to deal with that. The game isn't going to be fresh and new again, not like those first days, no matter how many new games you try or how many ways you try to make the armor and weapons rules work. You're chasing a dead dream. Yes, you're addicted to that old juice, but that old juice ain't gonna make you high any more.
You need some new juice, friend.
Let's try an experiment. This is going to sound crazy, so chase everyone out of the room, close the door, put a chair under the knob, take a deep breath and then just let go of your natural doubts. No, this isn't the experiment. Not yet.
Find your favorite 20-sided die. Yes, you have one. If you have to take the chair away from the door because it's in another room, I'll understand. I'll wait. Good. Have you got it? Is the chair back in place? Then we can begin.
Roll the die. Go ahead, don't think about it, just roll it. Now take your eyes away and give the number as little thought as possible. There. That's how you normally roll that die.
Now, bring it up to your eye and stare at the die. Don't roll it. Just turn it over and over in your hand, very slowly, and concentrate all your attention on the object. ALL your attention. Push everything else out of your mind. Bring all the thoughts you have to bear on making the die the only object existing in the universe. Think about how it is going to look when you let it roll off your fingers onto the table. No, don't roll it, not yet. Just grok that one simple vision. The die rolling. You holding the die, you releasing the die, your eye following the die, the die coming to a rest.
Why does it matter? You are making it matter.
You are using your will to rid yourself of the clutter of emotions, of details, of random thoughts, of the stress that underlies your present moment in time - all that, so you can meditate on this die and give it power.
If you can muster any self-control at all, you will feel something. It won't be new or unique or something you haven't felt before. In fact, it will be a familiar feeling, a feeling you have whenever you become exceptionally conscious of what's going on around you. This is a feeling that you sometimes enjoy, that you sometimes dislike - but one that you associate with moments you remember.
Right now, this is a die in your hand. The die itself doesn't matter. The only thing that matters is how you choose to look at the die - right now, in your hand.
When you're ready - when you're completely ready - throw the die.
Now, sit down to start working on your world. Draw yourself together the same way you did with the die, only now, apply it to your world. Visualize the moment that you will run the place or the events you are creating right now. Push out everything else. Take your time. Don't rush. Live this moment. Be in this moment. Make it matter.
To have a deeply rewarding game experience doesn't require some special rule-system or game genre; it doesn't require a super-special DM or miniatures; it doesn't require a perfect space or great rolls for your character. You don't have to be 'in character' or possessed of detailed gear or magic character sheets. These things help but they're not required.
All that is required is you. Aware. Invested. Concentrating. Alive and in the moment.