"Some circumstantial evidence is very strong, as when you find a trout in the milk." (Henry David Thoreau)
There are two great branches of evidence in a Criminal Case. They are direct evidence and circumstantial evidence. The meaning of direct evidence is as plain as the nose on your face. A first grader can easily grasp the concept. Whatever a person perceives with any of his physical senses is direct evidence. If you see a crime happen that is direct evidence. And if you smell it or touch it or taste it or hear it as it happens -- that is also direct evidence. Everything else is circumstantial. Therefore, the meaning of circumstantial evidence is easily comprehended and just as easily categorized. If it isn't direct evidence it's circumstantial evidence. And if there's a trout in a can of milk, we know the farmer has dipped his can into a stream of water. We didn't see him do it, but we know the squiggly rainbow didn't come from a cow's udder. The finned scrapper getting his first taste of milk is irrefutable circumstantial evidence of dairy farmer duplicity!