Book excerpt: A visual exploration of the universe that exists within our own bodies. Within our bodies hides an entire world of organisms called microbes. They boost our immune systems, digest our food, regulate our metabolism and even impact on our mental health. Through Katie Brosnan’s personable illustrations, we follow the digestive process from the moment the food enters our mouths to the moment waste leaves our bodies. Along the way we learn about this fascinating scientific frontier and gain an insight into the vast ecosystem that exists inside us.