See, hear, smell...
We experience our sensations so everyday that they seem almost banal. But these windows into the world speak different languages - sound and touch are physical stimuli, smelling and tasting chemical, seeing lies between waves and particles - and all these physical languages must be translated into those of the nerves. But this is where the miracles from the engine room begin.
Further up, on the more psychological levels, perceptions are deceived and there are interesting effects. Also exciting: Why can we perceive beauty? And then there's us - more precisely: our self. This is also a matter of perception.