Hi! We're on Part Three right now. :)
On chapter one, we've learned that we experience everything in this world using our five senses: eyes, nose, ear, tongue and nerve. Those senses are called 'modalities' in NLP.
On chapter one we've also learned that what we see is not the representation of the real world--since our senses can only take datas limitedly. What we have is only our perception of the world.