The world exists only as metaphor. By the world I mean this experience we call reality, or life itself. This is literally true as you never directly interact with anything in your life, instead you deal with mental projections of the physical thing. This doesn't actually taste like strawberry, my brain is just telling me it does. Flavors are merely signals, catalyzed by chemicals, and interpreted by our nervous system; every quality an object might have is merely the interpretation of it by our brains.
These interpretations are put together to form a picture, right now my picture is one where I am sitting down, at work, typing out my ideas. To create this picture, my brain is combining memories, spatial awareness, and input from my senses. These pieces of the picture come together like a puzzle and are presented to me in the form of life/existence/reality/the world. However, none of the pieces would fit anywhere unless there were other pieces to fit in to. My interpretation of the world only makes sense when compared to something else.
What else is there to compare the world to? Humans are carriers of things that may not exist in the universe, manifestations of ideas. Some of our manifestations do exist, such as tables and cars. Others are more complex and may not exist, like utopia or teleportation. During the process of turning an idea into reality, we continually compare our progress with our idea. We navigate the world in much the same way; in our minds we construct a model that makes sense to us, then act according to the predictions of this model.
This model cannot simply be false or wrong, it is based on some semblance of objective reality. All are not equal, some models are closer to reality than others. Those that are closest to reality are of the greatest worth as they allow the most accurate interpretations of sensory input. These models allow predictions of the future; if I do not eat then I will be hungry, if we lower interest rates then the economy will improve, etc. The best models of reality yield the most accurate predictions.
Each of us has a model of reality, a way we think the world works. Even if you feel you don't understand how the world works, that knowledge of your own fallibility is part of your model. You see the holes because they are big, but you understand exactly what you need to understand in order to survive, otherwise you wouldn't be here! (Or know how to read for example.)
Every instant you are unconciously comparing your sensory input to your model of the world. This is how you walk: your brain takes nerve cell transmissions from your legs, orientation information from your inner ear, and spatial information from your eyes, to compute where your foot should go. This is how you make decisions, you consult your model of the world to decide which action will get you what you want.
Your model is not a thing which exists in objective reality, it exists only through its effects on your actions. For example: if your model includes a bit about examining and improving your model, then your ability to make accurate predictions will increase. In this way you can further your goals through more deliberate actions. By improving your model of the world, you alter your actions to better fit the world.
Improving your model is a form of meta-thinking, thinking about your thinking. A headache is normal here, your brain doesn't have a mirror to see itself in so it struggles a bit. This can be dangerous too, the goal of meta thinking is to literally change how you think and that can go many ways. In order to prevent yourself from erring and changing your model for the worse, you must take precautionary action in adjusting your mental metaphors.
Eventually every metaphor break down, Einstein's relativity fails at the quantum level just as 'The Economy' doesn't exist between two people. Your model has limits too, eventually you will experience something that does not fit. Your sensory input will tell you one thing but your model will say "that's impossible." What will you do then?
