We all live in two environments, the one being the world around us, the other our thoughts about that world. The larger world cannot affect us directly; it must be mediated to us by our thoughts, and will be to us at last only what we allow it to be.
Three men walking side by side may yet be inhabiting three different worlds. Imagine a poet, a naturalist and a lumberman traveling together through a forest. The poet’s mind races back over the centuries to the time when the mighty trees now towering above him were but beginning to appear as tiny green shoots out of the gray earth. He dreams of the mighty of the world who then wore crowns and swayed empires, but who have long ago passed from this earthly scene and been forgotten by everyone but a few historians.
The naturalist’s world is smaller and more detailed. He hears the sweet, hardly audible bird song that floats among the branches and seeks to discover the hidden singer; he knows what kind of moss it is that clings to the base of the centuries-old trees; he sees what the others miss, the fresh claw marks on the bark of a tree, and knows that a bear has recently passed that way.
The lumberman’s world is smaller still. He is concerned neither with history nor nature but with lumber. He judges the diameter and height of the tree, and by quick calculation determines how much it will bring on the market. His world is the dull world of commerce. He sees nothing beyond it.
It is obvious that one external world has been turned into three internal worlds by the thinking of the three men. External things and events are the raw material only; the finished product is whatever the mind makes of these.
2 Corinthians 10:5; Philippians 2:5
That Incredible Christian, 114, 115.