They cancel each other out: if you're vain about your chess abilities, they'll never advance very far, and if you're playing good chess, it means that, at least when it comes to the moves you've made in the game -- typically each player will move somewhere between 20 and 60 times in a game -- you're not kidding yourself, you're not dreaming, you're paying attention to the 64 squares in front of you and the 32 or fewer pieces on them. There are no grey areas, no room for subjective interpretation when it comes to the result of a game: you either win, lose or draw. This is perhaps even more clearly the case when you're playing chess against a computer program, or playing over the Internet with software which automatically detects game results and disallows moves which are against the rules and so forth.
One of the best chess players I've known personally once remarked that chess is a game of mistakes. (He was probably about a 2000-level player. I say probably because he had stopped playing in rated tournaments.) This seems to be true. What separates high level play from novices is the infrequency and subtlety of mistakes, but at any level, the player who wins, assuming my friend's remark was correct -- his level of chess is so far above mine, 800 or 900 points above, that I have to take his word about the nature of the game up there. I don't grasp it myself, not at all -- is the one who goofs the least often, who notices most often when his opponent goofs and who takes the best advantage of his opponent's mistakes. At my level blunders -- say, for instance, the opportunity to capture a piece without giving up any positional strength, or even the opportunity to checkmate the opponent right away -- sometimes go unnoticed for several moves.
In Internet chess, which is the type of chess I play most of the time these days, there is an additional type of mistake which can be made: the mouse slip. You meant to move a piece to a certain square, but your hand slipped on the mouse and the piece ended up somewhere else. Typically on Internet chess sites there is the possibility to give the opponent the opportunity to take back a move. On the site where I play, I've disabled this option. No takey-backies when you play me. If my hand slips when I'm moving, I live with the result. If you tell me your hand slipped -- well, for one thing, I wonder whether you're lying, and it wasn't your hand but your mind that slipped. And anyway, chances are I won't notice you trying to tell me anything during the game: I expand the chessboard to full-screen so that it covers the entire entire console where messages are exchanged. I didn't come to the website to chat, and I certainly don't want to talk during a game: feeble as my efforts are, they're the result of my attempt to concentrate fully on the game at hand. If I shrink the board so that I can see the console where players send messages, it's because my opponent hasn't moved in quite a while and I've become bored while waiting. If I see a private message to me from my opponent claiming that he had a mouse slip -- they're in bright yellow, they stand out from the steady stream of public messages -- I don't reply. Because I don't know any polite way to say: I don't care. Your mistakes are your responsibility. Mouse slips are an ever-present possibility in Internet chess. You ought to watch out for that.
There are currently over 20,000 rated players on FICS the site where I play. About four-fifths of them are better than I am. The result of every rated game affects both players ratings: if their rating are very close going in, and one player wins, the winner has 8 points added to his rating, and the loser drops 8 points. (On Blitz games, anyway, which include almost all the games I play there. Blitz means that each player has a total of between 3 and 15 minutes to make all of his moves, or he forfeits the game on time. Or there is incremental time-keeping which is reckoned to be equivalent: 2 minutes a side, for example, plus 12 seconds added every time you move. I don't like the incremental timekeeping, I've pretty much stopped playing games timed that way. On the website you can also play lightning games, with less time than blitz games, and standard games, with more time than blitz.) If the game is a draw, each player's rating stays the same. If the players' rating are mismatched, the higher player will win less than 8 points by winning and lose than 8 by losing the game, and in the event of a draw he will lose a couple of points, and the lower-ranked player stands to gain more and lose less. I've played a bunch of games there, and my rating -- that is, my Blitz rating. Most of the games played there are blitz games -- is currently 1130-something. Occasionally I've dropped lower than 1000 and risen higher than 1200. 1300 seems lie a beautiful grail to me. So, I'm not very good at all.
And I make no excuses about it. 16,000 or so players are rated above me in blitz chess on FICS. That means they're playing better chess than I, no more, no less. I make no excuses, and I have no interest in the excuses other players make. Your mouse slipped? Bummer. Your boss busted you and you want to adjourn the game? That sort of thing's gonna hurt your rating, Sparky. You didn't mean to move there? I know the feeling, it sucks.
There are some players, playing in cyberspace and also in 3-D, in the meat world, who give and take takebacks all the time, routinely. It doesn't seem to me that they're really playing chess. Seems to me they're refusing to learn how to play it for realsies. In baseball, or even in the most casual slow-pitch softball game, you don't get do-overs because your hand slipped on the bat or because you missed a fly ball because the sun was in your eyes.
So what's my point, anyway? I'm not sure. I think it may be just that a lot of life is very murky and uncertain and subjective and mysterious, and that chess may be comforting because it can be a complete contrast to all of that, even if it is only a meaningless game played for no stakes other than for its own sake.
PS, 28. August 2012: I've been getting a little better: my current rating is 1263, and my best is 1329, which I reached on 2. April 2012. (And FICS continues to grow and improve, 1329 represents a higher level of play in 2012 than it did in 2009, just as it would in the world of tournaments.) Now 1400 and beyond is the possible-seeming grail.