The bear sees the squirrel. The dog needs the squirrel. The mouse chases the squirrel. The squirrel chases the bear. If someone needs the dog then the dog sees the bear. If the dog is rough and the bear does not need the dog then the bear chases the squirrel. If the bear chases the squirrel and someone does not chase the bear then they do not need the bear.
The bear needs the dog.