Exposure to microbes is not the only way children can benefit from messy play in nature—it’s also the ultimate sensory experience. Walking barefoot across a log, sinking your hands into a pile of mud, listening to the birds singing, and feeling raindrops land on your forehead are all stimulating to children’s senses. This is important because good sensory integration—i.e., our ability to process and organize the information that we get through our senses—means that our body and brain are functioning at their optimal level.