Let thine eyes look right on, and let thine eyelids look straight before thee.
How is your vision? Forget detail, distance, or depth. How is your directional vision? Do you see straight ahead, or do you have peripheral vision? Peripheral vision, or seeing things from the corner of your eye, is a good thing for driving and sports, but it is horrible for saints. You must see only one object - God, His kingdom, and His righteousness.
Having told you to keep your heart with all diligence (Pr 4:23), the Preacher warned against peripheral distractions, either left or right (Pr 4:26-27). You must establish your direction straight ahead and keep going in that direction - to the single goal of pleasing the Lord.
"Eyes" and "eyelids" are synecdoche, where part of a thing represents the whole. Solomon did not care about the little flap of skin that covers your eyeballs. He wanted your heart and mind and soul. He wanted all of you. In the last eight verses of this chapter, he lists ear, eyes, heart, flesh, heart, mouth, lips, eyes, eyelids, feet, and hand.
Your eyes select objects and direct your movements toward them, but it is your heart and mind that give and receive feedback from your eyes. Heart and eyes cannot be separated. It is your overall person, eyes included, you must keep in the way of wisdom.
The Lord Jesus taught against spiritual peripheral vision with similar language. And you should look unto Him as the great example of perfect vision for your soul (Heb 12:1-4). The context of His words will let you learn their sense and application (Matt 6:19-24).
"The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!" Matthew 6:22-23
Consider the context well. He condemned laying up treasure on earth, when you can lay up treasure in heaven, for your heart will follow your treasure (Matt 6:19-21). And He denied any man can serve two masters - God and mammon, or money (Matt 6:24).
He reasoned, if a man's natural vision directs his bodily movements, then a blind eye is a horrible thing, for the body cannot know where to move. Considered spiritually, an eye with undivided honesty and zeal for God will lead to holiness, but a double eye of hypocrisy and worldly lusts will lead to destruction. Mark the Saviour's warning!
Consider an obscure reference to soldiers in Chronicles. Zebulun brought 50,000 fighting men who were of one heart for David (I Chron 12:33). They had no mixed emotions. They were not thinking about going home. They were not thinking about anything else.
Jesus rejoiced to see Nathanael, for his heart was free from duplicity, hypocrisy, and a double mind (John 1:47). He was an Israelite indeed, fully committed to his God.
The Christian life is a race (I Cor 9:26; Heb 12:1). To win, runners must look straight ahead without being distracted by competitors or other things. Paul pressed forward, not looking sideways, to win the prize of God's high calling (Phil 3:13-14), and he described those with peripheral vision for worldly things as belly worshippers (Phil 3:18-19).
Wicked men have a double heart (Ps 12:1-2). They are not totally committed to the Lord and spiritual things. Their hearts still lust after this world and its things. They are carnally minded, and they show little evidence of grace in their hearts. You can easily spot them, for they never talk about the Lord with the same passion as their own things.
James warned twice against being double minded - or having more than one objective for your life (James 1:8; 4:8). He said a double minded man is unstable in all his ways, and he exhorted saints to diligent efforts to reduce their objectives to only one (James 4:8-10).
Eve was seduced by her wandering eyes (Gen 3:6). Lot's wife could not keep from looking back (Gen 19:17,26). Achan saw Babylonian goods and money that cost him his life (Josh 7:21). And David took what he saw one night from a rooftop (II Sam 11:2).
Your prayer should be for God to keep your eyes from seeing vanity (Ps 119:37). The lust of the eyes is one of the great temptations of man (I John 2:15-17). So careful was Job in his pursuit of holiness, he made a covenant with his eyes against thinking upon young beautiful women (Job 31:1). Contrast him with false teachers (II Pet 2:14).
The first church, under the powerful influence of the Holy Ghost, had a single mind with God and each another (Acts 2:46). They were undivided in their dedicated and solitary ambition of serving the Lord. Things in the corner of their vision did not distract them.
Godly men serve masters with single hearts (Eph 6:5; Col 3:22). Their solitary goal is to please the Lord on the job, regardless of what men may think or do. They do not seek a raise or promotion as their principal objective, for they see only God's reward.
Dear reader, what distracts your vision and progress? You need only one goal - pleasing God with a holy life and preparing for heaven. Put on your blinders and keep your eyes and motion straight ahead. Look only forward - only upward - and only heavenward!
Did the Lord Jesus have any other objectives in His life on earth? None! Did things around Him distract him? Never! Though he had food, honor, and glory offered to Him by the devil, He remained absolutely faithful to His one goal - pleasing His Father by a perfect life and death! Glory! Follow this great Example and His singular vision!