Sometimes it's just half a cup

I was asked this question (again) a short while ago. "Is half a cup, half full or half empty?" Tough question. I had to think about it and yes, there is a difference. It depends which way the level of liquid is going. If you fill the cup only halfway, it is half full, as you didn't fill it right up to the top. If, however, you fill it completely, and then drink it to the halfway, it is half empty. You can's fill a cup half empty, and you can't drink a cup half full.

There's an exception to this. If you are drinking your drink, say, in a bar, and you forget your glass on the table. Then you turn back to it, it can have both, half full and half empty conditions depending on your memory (or optimism/pessimism). If you thought "gosh, I need to get another drink in a while, as my drink was almost finished" and you see the half-filled glass, you shout in your head: "Hey! It's still half-full!" - If, on the other hand you're thinking "ah, still got almost a full glass, lemme take a sip... Hey! It's already half empty!"

My conclusion is: A pessimist would have a half full cup, while an optimist would have a half empty one.