The intricacies of sport never cease to remind us that minuscule margins can prove so decisive. The shot in soccer that hits a crossbar and bounces down onto or over the line -- depending upon the referee's view -- can have a cataclysmic effect upon a team's fortunes.
In golf, a player can perform at his peak for four long days, 72 holes in all, and miss out on victory in a major tournament by a single putt that brushes the hole yet stays out.
Last weekend's opening round of the Six Nations Championship reminded us that rugby is as prone to these marginal decisions as any other game.
By common perception; France were a revelation; England much improved; Scotland swept aside; Wales ordinary; Ireland poor and Italy weak. Yet in the case of almost every team, tiny percentages entered the equation and had a significant effect.
Granted, the French were genuinely too strong on the day in Paris for the Scots. But, in the other two games, the margins were small. Quite possibly, had Italy reclaimed a restart kick with less than four minutes left, kept the ball and not turned it over to concede the field position, Declan Kidney's men may well have succumbed.
Or would they? Had Brian O'Driscoll done what he has done a thousand times in his career and accurately lobbed a miss-pass to an unmarked wing, in this case Fergus McFadden, after 56 minutes, Ireland would have been in.
Two minutes later, Gordon D'Arcy lost the ball in a combined tackle just a yard or two from the Italian line, and those were by no means the only scoring chances Ireland created.
But had they taken just one of them and converted a try, it would almost certainly have been a very different denouement to the one that unfolded.
Yet Italy too could point to some critical moments when the margin between victory and defeat had come down to a few feet. Had Mirco Bergamasco's conversion attempt of Luke McLean's 75th-minute try succeeded, Ireland would have needed a try to secure victory. A drop goal would only have been enough for a draw.
And if Bergamasco had landed a 40-metre penalty after half an hour which looked pretty straightforward at this level, Italy would have enjoyed a bigger half-time lead.
Even in Cardiff, where England looked much the better side, Wales could curse one defensive aberration, a palpable lack of concentration which allowed fly-half Toby Flood to march through a gap as big as a farmyard gate and put wing Chris Ashton over for a try by the posts which was, inevitably, converted.
Had that one incident not occurred, Wales would have saved themselves seven points. And what was England's final victory margin? Yes, seven points. In every game, any side can probably point to a single moment which ultimately proved so costly.
And what this exercise does is demonstrate that, not only is the margin between victory and defeat very often minuscule, but there is not much difference between any of the sides in this Six Nations Championship.
There has been a general levelling up so that, in most cases, any side can upset another on a given day. Okay, in rugby terms, if you find yourselves on the wrong end of an inspired performance by one team, you're going to cop it big time.
A missed conversion or single try here or there isn't likely to make much difference. But, it is surprising how few times that really happens. In most instances, any team can look back at a game and pinpoint one or two specific instances where they either lost it, or just scrambled home.
If you accept this argument, then you should subscribe to the theory that Ireland has everything to play for against the French on Sunday. Sure, the French dazzled and delighted in Paris last weekend while the Irish dithered and dallied in Rome.
But that was then and this is now. Matches this weekend won't be won by last weekend's memories. Every side, like every golfer and every other sportsman, has to go out and do it all again the next day, or in this case the next week, remembering all the while that one mistake -- one missed kick or dropped pass -- could cost a team victory.
And so, I finish with a blunt message for the player about to lose his head and charge into a ruck from the side, thereby incurring a potentially vital penalty -- think of the possible consequences.