You're driving a car.
Or simply sitting by the window looking out at the garden.
You suddenly notice that the window pane is dirty - it has all these smudges.
And then you realize it. If you're too busy focusing on the smudge, then you really don't see where you're going; you cannot appreciate the beauty of the blooms. And if you're focusing on the road ahead, or the lovely sight of the flowers in that garden - you don't really notice those smudges on the pane; you don't quite "see" them.
You can focus only on one thing at a time. You always have that choice.
So, what are you looking at - the smudge, or something beyond?