How is this an imagery The water warm too for it has slipped twinkling over the yellow sands in sunlight before reaching narrow pool?

This is an example of visual imagery. The writer uses descriptive language to create a picture in the reader's mind. In this case, the writer is describing a pool of water that is warm and reflects the sunlight. The water is also flowing over yellow sands, which adds to the visual effect. The use of words like "twinkling" and "narrow" also helps to create a vivid image.