cloud in a picture, and let a, b, c, d, etc., be the related facts, or the shape, size, color, etc., of the cloud. The arrows indicate the passing of our thought from cloud to related fact, or from related fact to cloud, and from related fact to related fact. As long as these related facts lead back to the cloud each time, that long we are attending to the cloud and thinking about it. It is when our thought fails to go back that we "wander" in our attention. Then we leave a, b, c, d, etc., which are related to the cloud, and, flying off to x, y, and z, finally bring up heaven knows where.