Thanks for the wonderful post zinnia!

I think the glass half full/half empty trope is misleading. I know I know - it's meant to be a metaphor on the importance of perspective... and it's a good one too. But the fundamental fact is that the glass is ALWAYS 100% full, 100% of the time. In this particular example, half of the cup is filled with LIQUID, and the remaining half is filled with AIR. (Air isn't nothing - it's just a less dense version of matter.)

What matters in your cup?