An absolute, Marty McFly-kind of truth with a touch of the chaos theory. Or at least it could be, if you believe in these kind of things.

This always is the first step of reconsideration when I start thinking "what if ... enter random thing that, had it been different, could improve any given situation"

When you start making changes in the past like that, you must realise that anything else might as well have changed too. There's no beginning and no end to it - you cannot possibly believe that one tiny or (if you're an optimist) immense change could be an isolated phenomenon.

I usually end up thinking things like: "If I'd left my house 5 minutes earlier I'd've been dead." Which seems a bit harsh, just to catch a train.