Doughnut
Pessimist sees hole, optimist sees doughnut. Pessimism not very good for filling tummy. Leads to upset stomach over time. Eating too many doughnuts not good either. The usual Taoist best described as realist, knowing that yin and yang is about holes and doughnuts oscillating back and forth. Sometimes we get hole, sometimes we get doughnut, but am always open minded to same.