A person’s ability to control† their perception of what is (real) is directly related to their ability to control their reality.
Which can be (very) roughly translated as:
What you SEE is what you get. (WYSIWYG)
† Our individual perception passes through many ‘filters’ in our brain that we have developed throughout life experience, with a little help from evolution. If we do not recognise these and how they affect our thinking, or the way we see things, we are powerless to do the things we might be able to do if we were not so restricted. The ‘control’ comes in because if we ever were to attempt to perceive something in it’s entirety – as it really, fully and truly IS – our limited brain would be far too overloaded to function appropriately. The filters serve a valuable function, but like a good photographer we need to be able to understand what each filter does for us – as well as what it prevents us from seeing – then choose wisely and as appropriate for the picture (or version of our reality) we wish to see.