frequencies

This story is about a theory i read. The theory is thar there are a lot of things going around us but, as humans frequencies are fix the see and hear something they are not visible and audible to us. Thats why we say that animals can sense spirits because their frequencies arr a little lower or higher than ours. The story is from a man's pov who can sense these spirits as well. How is the world for him? You will find out in the story.