[Mat 6:19-23 KJV] Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal: But lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal: For where your treasure is, there will your heart be also. 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!

[2Pe 2:4-8 KJV] For if God spared not the angels that sinned, but cast [them] down to hell, and delivered [them] into chains of darkness, to be reserved unto judgment; And spared not the old world, but saved Noah the eighth [person], a preacher of righteousness, bringing in the flood upon the world of the ungodly; And turning the cities of Sodom and Gomorrha into ashes condemned [them] with an overthrow, making [them] an ensample unto those that after should live ungodly; And delivered just Lot, vexed with the filthy conversation of the wicked: (For that righteous man dwelling among them, in seeing and hearing, vexed [his] righteous soul from day to day with [their] unlawful deeds;)

If your eye is SINGLE;
ἁπλοῦς haploûs, hap-looce’; probably from G1 (as a particle of union) and the base of G4120; properly, folded together, i.e. single (figuratively, clear):—single.

If your eye be EVIL;
STRONGS NT 4190: πονηρός
πονηρός (on the accent cf. Lob. ad Phryn., p. 3 Göttling, Lehre v., Accent, p. 304f; (Chandler §§ 404, 405); Lipsius, Grammat. Untersuch., p. 26), πονηρά, πονηρόν; comparitive πονηρότερος (Matthew 12:45; Luke 11:26); (πονέω, πόνος); from Hesiod (Homer (ep. 15, 20), Theog.) down; the Sept. often for רַע;
1. full of labors, annoyances, hardships;
a. pressed and harassed by labors; thus Hercules is called πονηροτατος καί ἄριστος, Hesiod fragment 43, 5.
b. bringing toils, annoyances, perils: (καιρός, Sir. 51:12); ἡμέρα πονηρά, of a time full of peril to Christian faith and steadfastness, Ephesians 5:16; Ephesians 6:13

In seeing and in hearing, Lot VEXED his soul;
βασανίζω basanízō, bas-an-id’-zo; from G931; to torture:—pain, toil, torment, toss, vex.

The eye is the light of the body. What do I choose to “see” on a day to day basis?

[Phl 4:8 KJV] 8 Finally, brethren, whatsoever things are true, whatsoever things [are] honest, whatsoever things [are] just, whatsoever things [are] pure, whatsoever things [are] lovely, whatsoever things [are] of good report; if [there be] any virtue, and if [there be] any praise, think on these things.

THINK;
λογίζομαι logízomai, log-id’-zom-ahee; middle voice from G3056; to take an inventory, i.e. estimate (literally or figuratively):—conclude, (ac-)count (of), + despise, esteem, impute, lay, number, reason, reckon, suppose, think (on).

There is in the chapters 2 and 3 of Revelation, a picture painted, a message portrayed that needs no speech or language. It is a message written in a way anyone can “see” it. The message unfolds withing the golden candlesticks. Psalm 19 tells you of a powerful teaching tool that does not require language. It tells you that the tabernacle, as oriented with the gates on the East, teaches you things when you take into account, the rising of the sun in the East (the camp of Judah) and it’s journey out of the outer court (the visible world) into and through the holy place (place of the candlestick and show bread), and through the veil on into the holiest place.

The camp of the South, as prescribed in conjunction with the orientation of the tabernacle, was the camp of Reuben, Gad and Simeon. Reuben means “see”, Simeon means “hear”, Gad means “troop/assembly”.

Assembly for seeing and hearing.

Hence, in the assemblies, the churches, we read the admonition seven times, once in each different assembly:

He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the tree of life, which is in the midst of the paradise of God. …

He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death. …

He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the hidden manna, and will give him a white stone, and in the stone a new name written, which no man knoweth saving he that receiveth [it]. …

He that hath an ear, let him hear what the Spirit saith unto the churches.

He that hath an ear, let him hear what the Spirit saith unto the churches. …

He that hath an ear, let him hear what the Spirit saith unto the churches. …

He that hath an ear, let him hear what the Spirit saith unto the churches.

Seeing is also a quality of the mature individual. Not communal seeing, but the God given faculty of seeing for yourself:

[Mat 15:14 KJV] Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.

[Luk 6:39 KJV] And he spake a parable unto them, Can the blind lead the blind? shall they not both fall into the ditch?

There is a further truth which when understood and employed, gives detail to the messages of the tabernacle. Those born free and those born to bondage can not be heirs together:

[Gal 4:30 KJV] Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman.

[Gen 21:10 KJV] Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, [even] with Isaac.

(***note: these spiritual truths apply to all. There is no bond or free in Christ. No distinction of flesh. Hence, though the Holy Ghost uses these distinctions to paint pictures, He applies none of them to them who exercise faith)

There are in the camps of the tribes, 7 born to wives (Rachel and Leah), 4 born to bondwomen (Bilhah and Zilpah) To see for yourself that the scriptures make a difference when teaching spiritual things, see Gen.37, the generations of Jacob, and Ruth 4, the building of the house of Israel.

In the camp, Gad, Dan , Asher and Naphtali are sons of bondwomen. Gad is in the South (the camp of the candlestick) and means “troop/assembly”. Dan, Asher and Naphtali comprise the entire North camp. If you “cast out the bondwomen and their offspring”, the assembly is gone from the South, and all that remains is “seeing and hearing” with no assembly involved. And the entire North camp is eliminated. So, what it means (another lesson) is eliminated, and all that remains to see and hear, is what passes before you from East to West. One arises out of Judah, passes through the camp, and enters the holiest, becoming seated therein.

This is what the “single” eye of the saint sees. Christ, what He is, who He is, What He has done, and how you by faith, accompany Him. None of what is “seen” takes place in the world at large, except the once and for all sacrifice and offering of Himself for sin. Once ascended, all seeing and hearing Him, are seeing and hearing Him where He is:

[Jhn 14:22-23 KJV] Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world? Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.

Condensed message: Seeing and hearing the world on a continual basis is vexation of spirit. Seeing and hearing Christ results in a body full of light.

For the more-than-casual student of scripture, there is another message written into the tabernacle. It is the generations of Jacob (which means deceiver). It too, is seen by eliminating them born free. It is the house of bondage, composed entirely of the troop (Gad in the South) and the seat of the camp of judgment (Dan), things that sound good (Naphtali) and junk food, fat bread and dainties (Asher)

[Gen 49:16-17 KJV] Dan shall judge his people, as one of the tribes of Israel. Dan shall be a serpent by the way, an adder in the path, that biteth the horse heels, so that his rider shall fall backward.

The entire house of bondage, the North-South Assembly, can be read of in Isaiah 14. It is what must be taken away in order for the WAY into the holiest to be revealed, as Paul also knew and expounded in Hebrews 9.