The phrase ‘the map is not the territory’ encapsulates the first. We respond to the world
around us through the five senses and how we perceive things. This involves a complex
set of filters, which turn outside reality into subjective experience – in other words,
‘experience’ unique to the person and based upon their beliefs, values, feelings, life
experience and so on. We then act according to our filtered map of the world – the only
world we know. We cannot know reality because of the way our mind structures and
processes it as ‘experience’. Our mental map seems like reality, but in fact can never
equate to reality, or the ‘territory’. The NLP presuppositions in the next chapter reflect
these important fundamental concepts.
These processes inter-relate with other systems, both inside the person and also
embracing the people around and the wider environment. We act not independently,
but systemically and holistically. So we cannot isolate any part of these systems – such
as a specific behaviour – from the rest.

Alder, Harry. Handbook of NLP : A Manual for Professional Communicators.

So then is it ever possible to truely know reality or just have our own experience of it?

I believe many people model the reality of some 'things' very closely within their minds.

Consider the surgeon who does triple heart bypass operations successfully, day after day.
What about the space explorers who achieve their objectives?

Where we seem to be clutching at straws is with those concepts which may only reside within some brains, ie., with concepts which cannot be proved, like religion (faith), ghosts, philosophy, the best way forward etc.

This does not mean man has conquered the world; there remain many unknowns in the outside world too!