On the mountain in the distance before me, I see the huge oak and tulip trees swaying, with their leaves turned upward revealing the lighter green of their undersides. Waves of green, light and then dark, seem to cross the surface of the upper region from west to east as the leaves show the colors of their inner and outer sides. Parts of the hillside seem almost to breathe in and out as the trees bend away from me and back. It is a familiar sight, and I immediately realize that there is a wind. My belief that there is a wind is based on my belief that the trees are swaying. It is also justified on the basis of that belief. And if I know that there is a wind, I know it on the basis of my belief that they are swaying. In each case, one belief is inferentially based on another.