The Nose and Smelling

We have two noses, or even four. There are two separate entrances on the outside, the two nostrils. There are also two different ways of smelling. We can smell the air around us, but we also smell what is in our mouths. The world of smelling is a complex world, where food and (personal) hygiene (the use of soap, cleaner, perfume) come together: both heavily rely on the peculiarities of the sense of smell.