What do you think of this hypothesis? (You don't have to know much about neuroscience to understand this.)
I believe the main overall function of the brain is to imagine. To manifest to itself its own built in sense without the need for external stimuli. Considering this, I believe the eyes, ears, nose, tongue and skin receptors — although very useful — only serve as things that force the brain to use its imagining function and make the imagination correspond to external stimuli, thus becoming sense/perception. To sum it up, I believe the senses are imagination forced to behave with the outside world. What do you think?