What do I mean by reality? I mean that which has existence apart from any idea any mind may have of it, and which would exist if there were no mind anywhere to entertain a thought of it. That which is real has being in itself. It does not depend upon the observer for its validity.
I am aware that there are those who love to poke fun at the plain man’s idea of reality. They are the idealists who spin endless proofs that nothing is real outside of the mind. They are the relativists who like to show that there are no fixed points in the universe from which we can measure anything. They smile down upon us from their lofty intellectual peaks and settle us to their own satisfaction by fastening upon us the reproachful term “absolutist.” The Christian is not put out of countenance by this show of contempt. He can smile right back at them, for he knows that there is only One who is Absolute, that is God. But he knows also that the Absolute One has made this world for man’s use, and while there is nothing fixed or real in the last meaning of the words (the meaning as applied to God), for every purpose of human life we are permitted to act as if there were. And every man does act thus except the mentally sick. These unfortunates also have trouble with reality, but they are consistent; they insist upon living in accordance with their ideas of things. They are honest, and it is their very honesty which constitutes them a social problem.
The idealists and relativists are not mentally sick. They prove their soundness by living their lives according to the very notions of reality which they in theory repudiate and by counting upon the very fixed points which they prove are not there. They could earn a lot more respect for their notions if they were willing to live by them; but this they are careful not to do. Their ideas are brain-deep, not life-deep. Wherever life touches them they repudiate their theories and live like other men.
A. W. Tozer, The Pursuit of God