Pour yourself a glass of wine. Drink half. Now set the glass (half full or half empty?) on the table. Put objects around it to reflect light and color.
Now: look at it. What do you see? Pick a point on the glass. Focus all your attention on it. But be aware of the rest of your field of vision. What is in focus? What is out of focus? What colors do you see? Where do they come from? Be aware.