There is that one lesson that you learn again and again, and if you "learn" the same thing over and over, did you really learn anything?
Nothing really turns out the way you think it will. I mean it. Nothing. If you think about an upcoming event, or the next evening, or what you're going to do tomorrow, or how it's all going to work out, well, guess what? You are wrong. Almost always.
And if you aren't wrong, you never quite get it, you never get the nuance of the situation. You never really predict all the variables, and how you will experience it all. The experience is always more foreign, deeper, richer and surprising than you think it will be.
You'd think this would teach you to not expect, anticipate, figure on anything. But that seems stupid in a way. So you want to be the smart guy and you decide you know what to expect, but really that is the height of stupidity, a badge of not knowing anything.