Bird's-eye view
The book of Proverbs is intensely practical, and this verse is a prime example of that practicality. It sets up a sharp and telling contrast between the wise man and the fool. This is not an abstract, philosophical difference, but rather a difference in something as basic as where they direct their eyes. The man of understanding has wisdom right in front of him, accessible and immediate. The fool, on the other hand, is a master of distraction. His gaze is fixed on the horizon, on remote and irrelevant things, which is a convenient way to avoid the pressing duties of the here and now. This proverb teaches us that true wisdom is not found in esoteric knowledge or grand, global schemes, but in grappling with the mundane realities that God has placed directly in our path.
Clause-by-Clause Commentary
"Wisdom is in the presence of the one who understands..."
The Hebrew literally says wisdom is "before the face" of the man of understanding. It is right there. It is not something you have to order from a great distance, waiting for it to be shipped. It is not a treasure you must mount a grand expedition to find. For the one whose heart has been tuned by the fear of the Lord, which is the beginning of wisdom, the wise course of action is the obvious one. It is the next thing. It is the crying child that needs to be comforted, the bill that needs to be paid, the difficult conversation that needs to be had, the sin that needs to be confessed. Wisdom is located on your workbench, in the next room, at your desk. It is marvelously mundane.
The man of understanding sees it because he is not trying to escape his assigned station. He understands that God's will for him is not a mysterious riddle hidden in the clouds, but is rather revealed in the ordinary providences of a Tuesday afternoon. His duties are assigned to him from the outside; he does not get to make them up. This is why wisdom is "before him." He is looking for it in the right place, which is to say, right where he is.
"But the eyes of a fool are on the ends of the earth."
Here is the antithesis. The fool is not necessarily idle, but his activity is a form of idleness because it is completely detached from reality. His eyes are not on his own messy yard, but on how he would landscape the gardens of Babylon. He has a detailed plan for bringing about world peace, but he quarrels with his wife over breakfast. He is an expert on the theological controversies of the 16th century, but he does not catechize his own children.
Why are his eyes on the ends of the earth? Because distance provides a wonderful canvas for daydreaming. When your duties are far away, you can define them however you like. You can imagine yourself a great hero, a brilliant strategist, or a profound thinker, and because you never have to actually do anything, your self-assessment is never tested. This daydreaming grants a measure of what we could call "felt autonomy." The fool gets to be in charge. He fashions his own responsibilities and awards himself with as many imaginary honors as he can think of. The Internet has made this particular folly easier than ever; a man can be a lion in a comment thread and a mouse in his own living room.
The problem is not that we know what we should do and don't feel like it. The problem is that we do know what we should do, and we don't feel like it. The fool's gaze is a sophisticated mechanism for avoiding the obvious, assigned, and often humbling task that is right in front of his face. He would rather be anywhere else, doing anything else, because the "next thing" is not something he is in charge of, and it rubs his pride the wrong way.
Application
The application of this proverb is as direct as the proverb itself. Where are your eyes? Are you looking for wisdom in the abstract, in the hypothetical, in the grand scheme of things you cannot influence? Or are you looking for it in the concrete duties of your station?
Christian faithfulness is not lived out on a grand stage of our own choosing. It is lived out in the small corners of the world where God has placed us. It is about doing the next right thing, the obvious thing, the thing that is right there before your face. This is where holiness is forged. Changing the diaper, writing the report, showing kindness to the irritating coworker, speaking truthfully when it is costly, these are the atoms that make up a life of wisdom.
We must therefore repent of our "ends of the earth" foolishness. We must repent of the spiritual escapism that allows us to feel righteous for having strong opinions about distant evils while we neglect the cultivation of virtue in our own souls and homes. Ask God to give you an understanding heart, a heart that sees the profound importance of the mundane. Ask Him to give you the grace to embrace the station He has assigned you, and to find His wisdom waiting for you there, right in front of your face. For this is the pattern of the Lord Jesus Himself, who for the joy set before Him, did the next thing His Father gave Him to do, which was to endure the cross, despising the shame, for you.